Firestore App Check support

[raulgordejev]

https://firebase.google.com/docs/app-check

Firebase App Check now supports Firestore on iOS and Android. Would be awesome if the react native wrapper would also support this!

[mikehardy]

Hi there! We already do!

From your link:

When you enable App Check for a service and include the client SDK in your app,

So, if you include @react-native-firebase/app-check, and you go to your firebase console and toggle on appcheck for firestore (non-enforcing to start, right?) you should start seeing verified traffic.

Please note that using AppCheck in debug or CI environment currently is quite a pain, that's disccussed elsewhere in this repo - it is possible but not great (yet): #5660