refactor(iOS): move RCTNotifyEventDispatcherObserversOfEvent_DEPRECATED to const (#46833)

Summary:
This PR moves `RCTNotifyEventDispatcherObserversOfEvent_DEPRECATED` as it was used as string in the codebase and in OSS libraries.

## Changelog:

[IOS] [FIXED] - move RCTNotifyEventDispatcherObserversOfEvent_DEPRECATED to const

Pull Request resolved: https://github.com/facebook/react-native/pull/46833

Test Plan: CI Green

Reviewed By: cipolleschi

Differential Revision: D63891220

Pulled By: javache

fbshipit-source-id: d4fa1f751b4b0cb131ab6c6d4dd0a345762d7c71

packages/react-native/React/Base/RCTConstants.h

@@ -14,6 +14,8 @@ RCT_EXTERN NSString *const RCTUserInterfaceStyleDidChangeNotificationTraitCollec
 
 RCT_EXTERN NSString *const RCTWindowFrameDidChangeNotification;
 
+RCT_EXTERN NSString *const RCTNotifyEventDispatcherObserversOfEvent_DEPRECATED;
+
 /**
  * This notification fires when the bridge initializes.
  */

packages/react-native/React/Base/RCTConstants.m

@@ -21,6 +21,9 @@ NSString *const RCTJavaScriptWillStartLoadingNotification = @"RCTJavaScriptWillS
 
 NSString *const RCTDidInitializeModuleNotification = @"RCTDidInitializeModuleNotification";
 
+NSString *const RCTNotifyEventDispatcherObserversOfEvent_DEPRECATED =
+    @"RCTNotifyEventDispatcherObserversOfEvent_DEPRECATED";
+
 /*
  * W3C Pointer Events
  */

packages/react-native/React/CoreModules/RCTEventDispatcher.mm

@@ -58,7 +58,7 @@ RCT_EXPORT_MODULE()
   NSNotificationCenter *defaultCenter = [NSNotificationCenter defaultCenter];
   [defaultCenter addObserver:self
                     selector:@selector(_notifyEventDispatcherObserversOfEvent_DEPRECATED:)
-                        name:@"RCTNotifyEventDispatcherObserversOfEvent_DEPRECATED"
+                        name:RCTNotifyEventDispatcherObserversOfEvent_DEPRECATED
                       object:nil];
 }
 

packages/react-native/React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm

@@ -74,7 +74,7 @@ RCTSendScrollEventForNativeAnimations_DEPRECATED(UIScrollView *scrollView, NSInt
                                                                  userData:nil
                                                             coalescingKey:coalescingKey];
   NSDictionary *userInfo = [NSDictionary dictionaryWithObjectsAndKeys:scrollEvent, @"event", nil];
-  [[NSNotificationCenter defaultCenter] postNotificationName:@"RCTNotifyEventDispatcherObserversOfEvent_DEPRECATED"
+  [[NSNotificationCenter defaultCenter] postNotificationName:RCTNotifyEventDispatcherObserversOfEvent_DEPRECATED
                                                       object:nil
                                                     userInfo:userInfo];
 }