[RN] Use microtasks in the RN renderer based on a global flag defined by RN (#28472)

## Summary

We want to enable the new event loop in React Native
(react-native-community/discussions-and-proposals#744)
for all users in the new architecture (determined by the use of
bridgeless, not by the use of Fabric). In order to leverage that, we
need to also set the flag for the React reconciler to use microtasks for
scheduling (so we'll execute them at the right time in the new event
loop).

This migrates from the previous approach using a dynamic flag (to be
used at Meta) with the check of a global set by React Native. The reason
for doing this is:
1) We still need to determine this dynamically in OSS (based on
Bridgeless, not on Fabric).
2) We still need the ability to configure the behavior at Meta, and for
internal build system reasons we cannot access the flag that enables
microtasks in
[`ReactNativeFeatureFlags`](https://github.com/facebook/react-native/blob/6c28c87c4d5d8a9f5be5e02cd7d3eba5b4aaca8c/packages/react-native/src/private/featureflags/ReactNativeFeatureFlags.js#L121).

## How did you test this change?

Manually synchronized the changes to React Native and ran all tests for
the new architecture on it. Also tested manually.

> [!NOTE]
> This change depends on
facebook/react-native#43397 which has been
merged already

DiffTrain build for commit bb0944f.

Author: rubennorte

compiled-rn/facebook-fbsource/xplat/js/RKJSModules/vendor/react-test-renderer/cjs/ReactTestRenderer-dev.js

@@ -25454,7 +25454,7 @@ if (__DEV__) {
       return root;
     }
 
-    var ReactVersion = "18.3.0-canary-d46989150-20240312";
+    var ReactVersion = "18.3.0-canary-bb0944fe5-20240313";
 
     // Might add PROFILE later.
 

compiled-rn/facebook-fbsource/xplat/js/RKJSModules/vendor/react-test-renderer/cjs/ReactTestRenderer-prod.js

@@ -9175,7 +9175,7 @@ var devToolsConfig$jscomp$inline_1016 = {
     throw Error("TestRenderer does not support findFiberByHostInstance()");
   },
   bundleType: 0,
-  version: "18.3.0-canary-d46989150-20240312",
+  version: "18.3.0-canary-bb0944fe5-20240313",
   rendererPackageName: "react-test-renderer"
 };
 var internals$jscomp$inline_1194 = {
@@ -9206,7 +9206,7 @@ var internals$jscomp$inline_1194 = {
   scheduleRoot: null,
   setRefreshHandler: null,
   getCurrentFiber: null,
-  reconcilerVersion: "18.3.0-canary-d46989150-20240312"
+  reconcilerVersion: "18.3.0-canary-bb0944fe5-20240313"
 };
 if ("undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__) {
   var hook$jscomp$inline_1195 = __REACT_DEVTOOLS_GLOBAL_HOOK__;

compiled-rn/facebook-fbsource/xplat/js/RKJSModules/vendor/react-test-renderer/cjs/ReactTestRenderer-profiling.js

@@ -9603,7 +9603,7 @@ var devToolsConfig$jscomp$inline_1058 = {
     throw Error("TestRenderer does not support findFiberByHostInstance()");
   },
   bundleType: 0,
-  version: "18.3.0-canary-d46989150-20240312",
+  version: "18.3.0-canary-bb0944fe5-20240313",
   rendererPackageName: "react-test-renderer"
 };
 var internals$jscomp$inline_1235 = {
@@ -9634,7 +9634,7 @@ var internals$jscomp$inline_1235 = {
   scheduleRoot: null,
   setRefreshHandler: null,
   getCurrentFiber: null,
-  reconcilerVersion: "18.3.0-canary-d46989150-20240312"
+  reconcilerVersion: "18.3.0-canary-bb0944fe5-20240313"
 };
 if ("undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__) {
   var hook$jscomp$inline_1236 = __REACT_DEVTOOLS_GLOBAL_HOOK__;

compiled-rn/facebook-fbsource/xplat/js/RKJSModules/vendor/react/cjs/React-dev.js

@@ -26,7 +26,7 @@ if (__DEV__) {
     }
     var dynamicFlags = require("ReactNativeInternalFeatureFlags");
 
-    var ReactVersion = "18.3.0-canary-d46989150-20240312";
+    var ReactVersion = "18.3.0-canary-bb0944fe5-20240313";
 
     // ATTENTION
     // When adding new symbols to this file,

compiled-rn/facebook-fbsource/xplat/js/RKJSModules/vendor/react/cjs/React-prod.js

@@ -628,4 +628,4 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactCurrentDispatcher.current.useTransition();
 };
-exports.version = "18.3.0-canary-d46989150-20240312";
+exports.version = "18.3.0-canary-bb0944fe5-20240313";

compiled-rn/facebook-fbsource/xplat/js/RKJSModules/vendor/react/cjs/React-profiling.js

@@ -624,7 +624,7 @@ exports.useSyncExternalStore = function (
 exports.useTransition = function () {
   return ReactCurrentDispatcher.current.useTransition();
 };
-exports.version = "18.3.0-canary-d46989150-20240312";
+exports.version = "18.3.0-canary-bb0944fe5-20240313";
 "undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ &&
   "function" ===
     typeof __REACT_DEVTOOLS_GLOBAL_HOOK__.registerInternalModuleStop &&

compiled-rn/facebook-fbsource/xplat/js/react-native-github/Libraries/Renderer/REVISION

@@ -1 +1 @@
-d46989150e9225f2bf299dbca2270596d0829a58
+bb0944fe5bdd619be918621a9a1647204d6e7ce1

compiled-rn/facebook-fbsource/xplat/js/react-native-github/Libraries/Renderer/implementations/ReactFabric-dev.fb.js

@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<80123652bb9b7be7f517855aca5ff3f1>>
+ * @generated SignedSource<<9378c92e70cea9a594311fbdc67e5fa3>>
  */
 
 "use strict";
@@ -2987,8 +2987,6 @@ to return true:wantsResponderID|                            |
       enableUseRefAccessWarning = dynamicFlags.enableUseRefAccessWarning,
       passChildrenWhenCloningPersistedNodes =
         dynamicFlags.passChildrenWhenCloningPersistedNodes,
-      useMicrotasksForSchedulingInFabric =
-        dynamicFlags.useMicrotasksForSchedulingInFabric,
       useModernStrictMode = dynamicFlags.useModernStrictMode; // The rest of the flags are static for better dead code elimination.
     var enableSchedulingProfiler = true;
     var enableProfilerTimer = true;
@@ -5029,7 +5027,9 @@ to return true:wantsResponderID|                            |
     //     Microtasks
     // -------------------
 
-    var supportsMicrotasks = useMicrotasksForSchedulingInFabric;
+    var supportsMicrotasks =
+      typeof RN$enableMicrotasksInReact !== "undefined" &&
+      !!RN$enableMicrotasksInReact;
     var scheduleMicrotask =
       typeof queueMicrotask === "function" ? queueMicrotask : scheduleTimeout;
 
@@ -29801,7 +29801,7 @@ to return true:wantsResponderID|                            |
       return root;
     }
 
-    var ReactVersion = "18.3.0-canary-04bb7356";
+    var ReactVersion = "18.3.0-canary-61d1189b";
 
     function createPortal$1(
       children,

compiled-rn/facebook-fbsource/xplat/js/react-native-github/Libraries/Renderer/implementations/ReactFabric-prod.fb.js

@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<79ffaa0355a9d9b89df41eabe7496793>>
+ * @generated SignedSource<<15dc76ff98842d803f8a59fa78e23283>>
  */
 
 "use strict";
@@ -1278,8 +1278,6 @@ var alwaysThrottleRetries = dynamicFlags.alwaysThrottleRetries,
   enableUseRefAccessWarning = dynamicFlags.enableUseRefAccessWarning,
   passChildrenWhenCloningPersistedNodes =
     dynamicFlags.passChildrenWhenCloningPersistedNodes,
-  useMicrotasksForSchedulingInFabric =
-    dynamicFlags.useMicrotasksForSchedulingInFabric,
   scheduleCallback$3 = Scheduler.unstable_scheduleCallback,
   cancelCallback$1 = Scheduler.unstable_cancelCallback,
   shouldYield = Scheduler.unstable_shouldYield,
@@ -1601,8 +1599,11 @@ function cloneHiddenInstance(instance) {
     canonical: instance.canonical
   };
 }
-var scheduleMicrotask =
-  "function" === typeof queueMicrotask ? queueMicrotask : scheduleTimeout;
+var supportsMicrotasks =
+    "undefined" !== typeof RN$enableMicrotasksInReact &&
+    !!RN$enableMicrotasksInReact,
+  scheduleMicrotask =
+    "function" === typeof queueMicrotask ? queueMicrotask : scheduleTimeout;
 function getInstanceFromNode(node) {
   return null != node.canonical && null != node.canonical.internalInstanceHandle
     ? node.canonical.internalInstanceHandle
@@ -2329,7 +2330,7 @@ function scheduleTaskForRootDuringMicrotask(root, currentTime) {
   return currentTime;
 }
 function scheduleImmediateTask(cb) {
-  useMicrotasksForSchedulingInFabric
+  supportsMicrotasks
     ? scheduleMicrotask(function () {
         0 !== (executionContext & 6)
           ? scheduleCallback$3(ImmediatePriority, cb)
@@ -10625,7 +10626,7 @@ var roots = new Map(),
   devToolsConfig$jscomp$inline_1103 = {
     findFiberByHostInstance: getInstanceFromNode,
     bundleType: 0,
-    version: "18.3.0-canary-119507e5",
+    version: "18.3.0-canary-1aaf050f",
     rendererPackageName: "react-native-renderer",
     rendererConfig: {
       getInspectorDataForInstance: getInspectorDataForInstance,
@@ -10668,7 +10669,7 @@ var internals$jscomp$inline_1330 = {
   scheduleRoot: null,
   setRefreshHandler: null,
   getCurrentFiber: null,
-  reconcilerVersion: "18.3.0-canary-119507e5"
+  reconcilerVersion: "18.3.0-canary-1aaf050f"
 };
 if ("undefined" !== typeof __REACT_DEVTOOLS_GLOBAL_HOOK__) {
   var hook$jscomp$inline_1331 = __REACT_DEVTOOLS_GLOBAL_HOOK__;

compiled-rn/facebook-fbsource/xplat/js/react-native-github/Libraries/Renderer/implementations/ReactFabric-profiling.fb.js

@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<3a1a367017d4c9c4d53a27776b68c3f9>>
+ * @generated SignedSource<<d2ad8cf505447dec09fe24623849b875>>
  */
 
 "use strict";
@@ -1282,8 +1282,6 @@ var alwaysThrottleRetries = dynamicFlags.alwaysThrottleRetries,
   enableUseRefAccessWarning = dynamicFlags.enableUseRefAccessWarning,
   passChildrenWhenCloningPersistedNodes =
     dynamicFlags.passChildrenWhenCloningPersistedNodes,
-  useMicrotasksForSchedulingInFabric =
-    dynamicFlags.useMicrotasksForSchedulingInFabric,
   scheduleCallback$3 = Scheduler.unstable_scheduleCallback,
   cancelCallback$1 = Scheduler.unstable_cancelCallback,
   shouldYield = Scheduler.unstable_shouldYield,
@@ -1723,8 +1721,11 @@ function cloneHiddenInstance(instance) {
     canonical: instance.canonical
   };
 }
-var scheduleMicrotask =
-  "function" === typeof queueMicrotask ? queueMicrotask : scheduleTimeout;
+var supportsMicrotasks =
+    "undefined" !== typeof RN$enableMicrotasksInReact &&
+    !!RN$enableMicrotasksInReact,
+  scheduleMicrotask =
+    "function" === typeof queueMicrotask ? queueMicrotask : scheduleTimeout;
 function getInstanceFromNode(node) {
   return null != node.canonical && null != node.canonical.internalInstanceHandle
     ? node.canonical.internalInstanceHandle
@@ -2453,7 +2454,7 @@ function scheduleTaskForRootDuringMicrotask(root, currentTime) {
   return currentTime;
 }
 function scheduleImmediateTask(cb) {
-  useMicrotasksForSchedulingInFabric
+  supportsMicrotasks
     ? scheduleMicrotask(function () {
         0 !== (executionContext & 6)
           ? scheduleCallback$3(ImmediatePriority, cb)
@@ -11331,7 +11332,7 @@ var roots = new Map(),
   devToolsConfig$jscomp$inline_1184 = {
     findFiberByHostInstance: getInstanceFromNode,
     bundleType: 0,
-    version: "18.3.0-canary-ca9ab9fa",
+    version: "18.3.0-canary-7d52778b",
     rendererPackageName: "react-native-renderer",
     rendererConfig: {
       getInspectorDataForInstance: getInspectorDataForInstance,
@@ -11387,7 +11388,7 @@ var roots = new Map(),
   scheduleRoot: null,
   setRefreshHandler: null,
   getCurrentFiber: null,
-  reconcilerVersion: "18.3.0-canary-ca9ab9fa"
+  reconcilerVersion: "18.3.0-canary-7d52778b"
 });
 exports.createPortal = function (children, containerTag) {
   return createPortal$1(