Add C++ Turbo Module Event Emitter example (#44810)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/44810

Adds an example how to use the `EventEmitter` on a (C++) Turbo Module

## Changelog:

[General] [Added] - Add C++ Turbo Module Event Emitter example

Reviewed By: javache

Differential Revision: D57473949

fbshipit-source-id: 1a8d17fb83af4220ef12379e0102b5b2e233ed45

packages/rn-tester/js/examples/TurboModule/NativeCxxModuleExampleExample.js

@@ -9,6 +9,7 @@
  */
 
 import type {RootTag} from 'react-native/Libraries/ReactNative/RootTag';
+import type {EventSubscription} from 'react-native/Libraries/vendor/emitter/EventEmitter';
 
 import NativeCxxModuleExample, {
   EnumInt,
@@ -72,6 +73,7 @@ type ErrorExamples =
 
 class NativeCxxModuleExampleExample extends React.Component<{||}, State> {
   static contextType: React$Context<RootTag> = RootTagContext;
+  eventSubscriptions: EventSubscription[] = [];
 
   state: State = {
     testResults: {},
@@ -262,6 +264,34 @@ class NativeCxxModuleExampleExample extends React.Component<{||}, State> {
         'Cannot load this example because TurboModule is not configured.',
       );
     }
+    if (NativeCxxModuleExample) {
+      this.eventSubscriptions.push(
+        NativeCxxModuleExample.onPress.addListener(value =>
+          console.log('onPress: ()'),
+        ),
+      );
+      this.eventSubscriptions.push(
+        NativeCxxModuleExample.onClick.addListener(value =>
+          console.log(`onClick: (${value})`),
+        ),
+      );
+      this.eventSubscriptions.push(
+        NativeCxxModuleExample.onChange.addListener(value =>
+          console.log(`onChange: (${JSON.stringify(value)})`),
+        ),
+      );
+      this.eventSubscriptions.push(
+        NativeCxxModuleExample.onSubmit.addListener(value =>
+          console.log(`onSubmit: (${JSON.stringify(value)})`),
+        ),
+      );
+    }
+  }
+
+  componentWillUnmount() {
+    for (const subscription of this.eventSubscriptions) {
+      subscription.remove();
+    }
   }
 
   render(): React.Node {