Migrate React example app to react-scripts 5

Reviewed By: antonk52

Differential Revision: D35114197

fbshipit-source-id: 88b35b4d927d7eca099a62d9cf4319ffe3ecf423

js/react-flipper-example/src/index.tsx

@@ -16,5 +16,5 @@ ReactDOM.render(
   <React.StrictMode>
     <App />
   </React.StrictMode>,
-  document.getElementById('root')
+  document.getElementById('root'),
 );