Add EventEmitter code-gen support for C++ Turbo Modules (#44809)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/44809

Adding react-native-codegen parser support for a new `EventEmitter` property type on C++ Turbo Modules.

It is possible to later expand this feature to other languages (Java, ObjC).

## Characteristics

An `EventEmitter` must:
- be non null:
 `EventEmitter<string>` works, `?EventEmitter<string>` does NOT
- have a non null eventType:
  `EventEmitter<number>` works, `EventEmitter<?number>` does NOT
- have at most 1 eventType, `void` is possible as well:
  `EventEmitter<>` or `EventEmitter<MyObject>` work - `EventEmitter<number, string>` do NOT
- have a concrete eventType, `{}` is not allowed
  `EventEmitter<{}>` does NOT work
- be used in `Cxx` Turbo Modules only at this time

## Example

For these 4 eventEmitters in on an RN JS TM spec
```
  +onPress: EventEmitter<void>;
  +onClick: EventEmitter<string>;
  +onChange: EventEmitter<ObjectStruct>;
  +onSubmit: EventEmitter<ObjectStruct[]>;
```
We now generate this code:
1.) in the spec based header `{MyModuleName}CxxSpec` in the constructor:
```
      ... // existing code
      eventEmitterMap_["onPress"] = std::make_shared<AsyncEventEmitter<>>();
      eventEmitterMap_["onClick"] = std::make_shared<AsyncEventEmitter<OnClickType>>();
      eventEmitterMap_["onChange"] = std::make_shared<AsyncEventEmitter<OnChangeType>>();
      eventEmitterMap_["onSubmit"] = std::make_shared<AsyncEventEmitter<OnSubmitType>>();
```
2.) as `protected` functions
```
  void emitOnPress() {
      std::static_pointer_cast<AsyncEventEmitter<>>(delegate_.eventEmitterMap_["onPress"])->emit();
  }

  void emitOnClick(const OnClickType& value) {
      std::static_pointer_cast<AsyncEventEmitter<OnClickType>>(delegate_.eventEmitterMap_["onClick"])->emit(value);
  }

  void emitOnChange(const OnChangeType& value) {
      std::static_pointer_cast<AsyncEventEmitter<OnChangeType>>(delegate_.eventEmitterMap_["onChange"])->emit(value);
  }

  void emitOnSubmit(const OnSubmitType& value) {
      std::static_pointer_cast<AsyncEventEmitter<OnSubmitType>>(delegate_.eventEmitterMap_["onSubmit"])->emit(value);
  }
```

## Changelog:

[General] [Added] - Add EventEmitter code-gen support for C++ Turbo Modules

Reviewed By: javache

Differential Revision: D57407871

fbshipit-source-id: 2345cc6dacf0cb0d45f8a374ad9d4cbf8082f9d6