Support Firebase v9

[jhuleatt]

Description

v9 of the Firebase JS SDK introduces a new modular SDK to allow for smaller bundle sizes (details). Feedback is welcome in discussion #402!

Todo List

• Update deps: Firebase v9 and rxfire v6
• Update ReactFire source to new modular SDK style
• Update SDK handling (useFirestore, etc)
• Add a provider for every SDK (<FirestoreProvider sdk={firestore} />, etc)
• Add an async initializer for every SDK (useInitFirestore, etc)
• Update non-suspense-mode example app
  • Initialize Firebase app
  • Auth
  • Firestore
  • Realtime Database
  • Remote Config
  • Storage
• Update suspense-mode example app
• Update/add tests
  • Firebase app
  • Auth
  • Firestore
  • Realtime Database
  • Storage
  • useSdk
• Update docs
  • Regenerate reference docs
  • Update guides
  • Update README
  • Quickstart
  • v3 -> v4 upgrade guide

Out of scope for this PR, to be added later:

• Add more Performance Monitoring features #420
• Support firestore/lite #421

Code samples

See a sample in #402, and much more sample code in the modular-firebase branch.

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fixes #388

[atanaskanchev]

@jhuleatt Hi, is it possible to cut-off RC4 please?

[jhuleatt]

it possible to cut-off RC4 please?

@atanaskanchev thanks for catching that we didn't release a canary for the latest commit, looks like I broke the build while I was trying to diagnose something else. A new canary (reactfire@4.0.0-exp.2b31a5a) just released, and the latest will continue to be available at npm i reactfire@exp.

[akrawchyk]

this is awesome, thanks @jhuleatt!