Avoid string copy in event dispatching

Summary:
Changelog: [internal]

To avoid unnecessary string copy in event pipeline, use move semantics.

Event pipeline has ownership of event type. Passing it by reference ends up in a copy when `RawEvent` object is constructed. To avoid this, pass string by value through each layer and use move semantics to avoid extra copies.

Reviewed By: javache

Differential Revision: D34392608

fbshipit-source-id: c11d221be345665e165d9edbc360ba5a057e3890

ReactAndroid/src/main/java/com/facebook/react/fabric/jni/EventEmitterWrapper.cpp

@@ -19,7 +19,7 @@ EventEmitterWrapper::initHybrid(jni::alias_ref<jclass>) {
 }
 
 void EventEmitterWrapper::invokeEvent(
-    std::string const &eventName,
+    std::string eventName,
     NativeMap *payload,
     int category) {
   // It is marginal, but possible for this to be constructed without a valid
@@ -35,7 +35,7 @@ void EventEmitterWrapper::invokeEvent(
 }
 
 void EventEmitterWrapper::invokeUniqueEvent(
-    std::string const &eventName,
+    std::string eventName,
     NativeMap *payload,
     int customCoalesceKey) {
   // TODO: customCoalesceKey currently unused

ReactAndroid/src/main/java/com/facebook/react/fabric/jni/EventEmitterWrapper.h

@@ -25,10 +25,9 @@ class EventEmitterWrapper : public jni::HybridClass<EventEmitterWrapper> {
 
   SharedEventEmitter eventEmitter;
 
-  void
-  invokeEvent(std::string const &eventName, NativeMap *params, int category);
+  void invokeEvent(std::string eventName, NativeMap *params, int category);
   void invokeUniqueEvent(
-      std::string const &eventName,
+      std::string eventName,
       NativeMap *params,
       int customCoalesceKey);