introduce RCTHostCreationHelpers

Summary:
Changelog: [Internal]
in this diff, i introduced a C function to be used to create RCTHost that obfuscates away all the C++ arguments. i expect this to be the API that the vast majority of the community will use to create `RCTHost`.

Differential Revision: D45678970

fbshipit-source-id: d3610b641498e17e628d8e346990dc346145b6b9

packages/react-native/ReactCommon/react/bridgeless/platform/ios/Core/RCTHostCreationHelpers.h

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import <React/RCTDefines.h>
+#import <UIKit/UIKit.h>
+
+@class RCTHost;
+
+@protocol RCTHostDelegate;
+@protocol RCTTurboModuleManagerDelegate;
+
+RCT_EXTERN_C_BEGIN
+
+RCTHost *RCTHostCreateDefault(
+    id<RCTHostDelegate> hostDelegate,
+    id<RCTTurboModuleManagerDelegate> turboModuleManagerDelegate);
+
+RCT_EXTERN_C_END

packages/react-native/ReactCommon/react/bridgeless/platform/ios/Core/RCTHostCreationHelpers.mm

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import "RCTHostCreationHelpers.h"
+
+#import <ReactCommon/RCTHermesInstance.h>
+#import <react/bridgeless/ReactInstance.h>
+
+#import "RCTHost.h"
+
+RCTHost *RCTHostCreateDefault(
+    id<RCTHostDelegate> hostDelegate,
+    id<RCTTurboModuleManagerDelegate> turboModuleManagerDelegate)
+{
+  return [[RCTHost alloc] initWithHostDelegate:hostDelegate
+                    turboModuleManagerDelegate:turboModuleManagerDelegate
+                           bindingsInstallFunc:nullptr
+                           jsErrorHandlingFunc:nullptr
+                              jsEngineProvider:^std::shared_ptr<facebook::react::JSEngineInstance>() {
+                                return std::make_shared<facebook::react::RCTHermesInstance>();
+                              }];
+}