Use paperTopLevelNameDeprecated in generated EventEmitters if defined (…

…#42812)

Summary:
Pull Request resolved: #42812

There is a way of defining events where you specify additional string type parameter in the EventHandler in the spec. This additional type parameter is an overridden top level event name, that can be completely unrelated to the event handler name.
More context here D16042065.

Let's say we have
```
onLegacyStyleEvent?: ?BubblingEventHandler<LegacyStyleEvent, 'alternativeLegacyName'>
```
This will produce the following entry in the view config:
```
topAlternativeLegacyName: {
  phasedRegistrationNames: {
    captured: 'onLegacyStyleEventCapture',
    bubbled: 'onLegacyStyleEvent'
  }
}
```
This means that React expects `topAlternativeLegacyName`.
But the generated EventEmitter looks like this:
```
void RNTMyNativeViewEventEmitter::onLegacyStyleEvent(OnLegacyStyleEvent $event) const {
  dispatchEvent("legacyStyleEvent", [$event=std::move($event)](jsi::Runtime &runtime) {
    auto $payload = jsi::Object(runtime);
    $payload.setProperty(runtime, "string", $event.string);
    return $payload;
  });
}
```
The native component will emit `legacyStyleEvent` (`topLegacyStyleEvent` after normalization) that React will not be able to handle.

This issue only happens on iOS because Android doesn't use EventEmitter currently.

To address this issue we'll use `paperTopLevelNameDeprecated` for the generated EventEmitters if it is defined.

Changelog: [iOS][Fixed] - Fixed support for event name override in component specs.

Reviewed By: cortinico, mdvacca, cipolleschi

Differential Revision: D53310654

fbshipit-source-id: 018d5b11d8d36e2ecf900b9d8d6fe3e2ed71f80b

packages/react-native-codegen/e2e/__tests__/components/__snapshots__/GenerateEventEmitterCpp-test.js.snap

@@ -190,7 +190,7 @@ Object {
 namespace facebook::react {
 
 void EventPropsNativeComponentViewEventEmitter::onChange(OnChange $event) const {
-  dispatchEvent(\\"change\\", [$event=std::move($event)](jsi::Runtime &runtime) {
+  dispatchEvent(\\"paperDirectName\\", [$event=std::move($event)](jsi::Runtime &runtime) {
     auto $payload = jsi::Object(runtime);
     $payload.setProperty(runtime, \\"value\\", $event.value);
 $payload.setProperty(runtime, \\"source\\", $event.source);
@@ -211,7 +211,7 @@ void EventPropsNativeComponentViewEventEmitter::onEventDirect(OnEventDirect $eve
 
 
 void EventPropsNativeComponentViewEventEmitter::onEventDirectWithPaperName(OnEventDirectWithPaperName $event) const {
-  dispatchEvent(\\"eventDirectWithPaperName\\", [$event=std::move($event)](jsi::Runtime &runtime) {
+  dispatchEvent(\\"paperDirectName\\", [$event=std::move($event)](jsi::Runtime &runtime) {
     auto $payload = jsi::Object(runtime);
     $payload.setProperty(runtime, \\"value\\", $event.value);
     return $payload;
@@ -220,7 +220,7 @@ void EventPropsNativeComponentViewEventEmitter::onEventDirectWithPaperName(OnEve
 
 
 void EventPropsNativeComponentViewEventEmitter::onOrientationChange(OnOrientationChange $event) const {
-  dispatchEvent(\\"orientationChange\\", [$event=std::move($event)](jsi::Runtime &runtime) {
+  dispatchEvent(\\"paperBubblingName\\", [$event=std::move($event)](jsi::Runtime &runtime) {
     auto $payload = jsi::Object(runtime);
     $payload.setProperty(runtime, \\"orientation\\", toString($event.orientation));
     return $payload;
@@ -238,7 +238,7 @@ void EventPropsNativeComponentViewEventEmitter::onEnd(OnEnd $event) const {
 
 
 void EventPropsNativeComponentViewEventEmitter::onEventBubblingWithPaperName(OnEventBubblingWithPaperName $event) const {
-  dispatchEvent(\\"eventBubblingWithPaperName\\", [](jsi::Runtime &runtime) {
+  dispatchEvent(\\"paperBubblingName\\", [](jsi::Runtime &runtime) {
     auto $payload = jsi::Object(runtime);
     
     return $payload;

packages/react-native-codegen/src/generators/components/GenerateEventEmitterCpp.js

@@ -369,9 +369,10 @@ function generateEvent(
   // In order to migrate to this new system we have to support the current
   // naming scheme. We should delete this once we are able to control this name
   // throughout the system.
-  const dispatchEventName = `${event.name[2].toLowerCase()}${event.name.slice(
-    3,
-  )}`;
+  const dispatchEventName =
+    event.paperTopLevelNameDeprecated != null
+      ? event.paperTopLevelNameDeprecated
+      : `${event.name[2].toLowerCase()}${event.name.slice(3)}`;
 
   if (event.typeAnnotation.argument) {
     const implementation = `

packages/react-native-codegen/src/generators/components/__tests__/__snapshots__/GenerateEventEmitterCpp-test.js.snap

@@ -361,7 +361,7 @@ Map {
 namespace facebook::react {
 
 void InterfaceOnlyComponentEventEmitter::onChange(OnChange $event) const {
-  dispatchEvent(\\"change\\", [$event=std::move($event)](jsi::Runtime &runtime) {
+  dispatchEvent(\\"paperChange\\", [$event=std::move($event)](jsi::Runtime &runtime) {
     auto $payload = jsi::Object(runtime);
     $payload.setProperty(runtime, \\"value\\", $event.value);
     return $payload;
@@ -370,7 +370,7 @@ void InterfaceOnlyComponentEventEmitter::onChange(OnChange $event) const {
 
 
 void InterfaceOnlyComponentEventEmitter::onDirectChange(OnDirectChange $event) const {
-  dispatchEvent(\\"directChange\\", [$event=std::move($event)](jsi::Runtime &runtime) {
+  dispatchEvent(\\"paperDirectChange\\", [$event=std::move($event)](jsi::Runtime &runtime) {
     auto $payload = jsi::Object(runtime);
     $payload.setProperty(runtime, \\"value\\", $event.value);
     return $payload;