Migrate to React 18

Summary:
Sadly, we have to use the experimental version of React to decapitate React Devtools.
See https://fb.workplace.com/groups/react.devtools/posts/3135684459978453/?comment_id=3135711763309056&reply_comment_id=3135760513304181

On the bright side, Replay.io and Code Sandbox also use experimental React without any problem.

Reviewed By: lblasa

Differential Revision: D34926473

fbshipit-source-id: 5cd63cc065c2535f0583464c7b5e37891dadaf14

desktop/flipper-ui-core/src/startFlipperDesktop.tsx

@@ -8,7 +8,7 @@
  */
 
 import {Provider} from 'react-redux';
-import ReactDOM from 'react-dom';
+import {createRoot} from 'react-dom/client';
 
 import {init as initLogger} from './fb-stubs/Logger';
 import {SandyApp} from './sandy-chrome/SandyApp';
@@ -164,10 +164,8 @@ function init(flipperServer: FlipperServer) {
 
   connectFlipperServerToStore(flipperServer, store, logger);
 
-  ReactDOM.render(
-    <AppFrame logger={logger} persistor={persistor} />,
-    document.getElementById('root'),
-  );
+  const root = createRoot(document.getElementById('root')!);
+  root.render(<AppFrame logger={logger} persistor={persistor} />);
 
   enableConsoleHook();