Add test case for set opacity in new arch examples (#47043)

Summary:
Part of this: #46757
Solves:
- ME2E0004

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[ Internal ] [ Added ] - Add setOpacity test in new-arch-example

Pull Request resolved: #47043

Test Plan:
```
yarn e2e-test-ios
yarn e2e-test-android
```

Reviewed By: cortinico

Differential Revision: D64457441

Pulled By: cipolleschi

fbshipit-source-id: 310270293f5c7ec8a94c0d38fdd0897e4591ec14

packages/rn-tester/.maestro/new-arch-examples.yml

@@ -30,3 +30,6 @@ appId: ${APP_ID} # iOS: com.meta.RNTester.localDevelopment | Android: com.facebo
     text: "Fire Legacy Style Event"
     repeat: 10
 - assertVisible: "Legacy Style Event Fired 10 times"
+- assertVisible: "Opacity: 1.0"
+- tapOn: "Set Opacity"
+- assertVisible: "Opacity: 0.8"

packages/rn-tester/NativeComponentExample/js/MyNativeView.js

@@ -166,6 +166,9 @@ export default function MyNativeView(props: {}): React.Node {
         Constants From Interop Layer:{' '}
         {UIManager.getViewManagerConfig('RNTMyLegacyNativeView').Constants.PI}
       </Text>
+      <Text style={{color: 'green', textAlign: 'center'}}>
+        Opacity: {opacity.toFixed(1)}
+      </Text>
       <Button
         title="Change Background"
         onPress={() => {