useAppCheck and/or preloadAppCheck

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).

[epodol]

A provider for App Check would probably be ideal. In my opinion, an activateCallback would be better because it would allow for more customization for individual use cases, and reduce any breaking api changes in the future if firebase changes the activate arguments.

[jhuleatt]

Thanks @MaciejCaputa for the feature request, and thank you @epodol for your temporary solution!

This is definitely an important feature to add to ReactFire. Let’s discuss a potential API. I wonder if we should have another Provider for AppCheck. It seems important to be able to be confident that AppCheck is activated before any calls are made that could be denied by AppCheck.

For example, it could look like:

<FirebaseAppProvider firebaseConfig={/* config... */}>
    <AppCheckProvider publicKey={/* recaptcha public key... */}>
        <MyChatApp />
    </AppCheckProvider>
</FirebaseAppProvider>

Then, I could be confident that any Realtime Database, Cloud Storage, or Cloud Functions (callable functions) calls that I make within <MyChatApp /> are made after AppCheck is activated.

This could also be done in FirebaseAppProvider, but separating it out may be good to reduce bundle size for those that aren’t using AppCheck.

The props for AppCheckProvider would likely have to account for all of the arguments activate accepts: siteKeyOrProvider : string | AppCheckProvider , isTokenAutoRefreshEnabled ? : boolean

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How does this sound to you? How can we make it better?