Hi, I think it would be a good idea to add useAppCheck and/or preloadAppCheck to provide functionality form https://firebase.google.com/docs/app-check

Version info

React: ^17.0.2

Firebase: ^8.7.1

ReactFire: ^3.0.0-rc.2

Steps to reproduce

1. Add import 'firebase/app-check';
2. Add useFirebaseApp().appCheck().activate('YOUR KEY')

Expected behavior

I have an app check working.

Actual behavior

Uncaught FirebaseError: AppCheck: You are trying to activate AppCheck for FirebaseApp [DEFAULT], while it is already activated. AppCheck can only be activated once. (appCheck/already-activated).