Support modular Firebase 9

[HofmannZ]

This PR adds support for Firebase 9. It does not change the API of next-firebase-auth, so the refactor for users of the package will be relatively simple.

This PR also updates the mocks, tests, and examples accordingly.

[gavinharris-dev]

Looks great! Just wondering should we also update the Readme (https://github.com/gladly-team/next-firebase-auth#using-the-firebase-apps)? You've already covered all the Examples which is great!

Although this is not really a breaking change for next-firebase-api it probably will be for existing applications as they will need to update to Firebase 9.0.0 right? - Does this change necessitate an few pointers to upgrading from Firebase v8? Even perhaps a link out to the Firebase official docs?

[HofmannZ]

@gavinharris-dev - Thanks for the feedback! I totally missed that readme section.

I think linking to the official docs would be great, this official article covers the upgrade: https://firebase.google.com/docs/web/modular-upgrade. I will also add a small example in the readme directly for ease of use.

[dukesx]

Any ETA on this ? At least Firebase UI is almost done migrating to Firebase 9. Its not official but the @next version seems to work pretty well. This package is now the only one waiting over a PR, that has already almost done everything for them. I wonder what's the wait. @HofmannZ Excellent Work and Kudos to you !

[HofmannZ]

@dukesx - I'm done as far as this PR is concerned. I also saw that the Gladly team is setting up pipelines for v1 of the next-forename-auth package 📦.

So, I assume this PR will soon be included in a prerelease of v1 🚀.

[codecov]

Codecov Report

Merging #291 (17251c5) into v1.x (9eefe04) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             v1.x     #291   +/-   ##
=======================================
  Coverage   99.58%   99.58%           
=======================================
  Files          25       25           
  Lines         484      484           
  Branches      167      167           
=======================================
  Hits          482      482           
  Misses          2        2           

Impacted Files	Coverage Δ
src/createAuthUser.js	100.00% <100.00%> (ø)
src/initFirebaseClientSDK.js	100.00% <100.00%> (ø)
src/useFirebaseUser.js	100.00% <100.00%> (ø)

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[kmjennison]

@HofmannZ Thanks for the thorough PR. Looks great. Only one change: could you resolve the merge conflicts in the README?

[vercel]

@HofmannZ is attempting to deploy a commit to the Gladly Team on Vercel.

A member of the Team first needs to authorize it.

[kmjennison]

@dukesx What version of firebaseui-web are you using that works well? This PR suggests a stable version with v9 support is a long way off, so maybe we can use an unstable release just to get the example app working.

[HofmannZ]

@HofmannZ Thanks for the thorough PR. Looks great. Only one change: could you resolve the merge conflicts in the README?

@kmjennison - Rebased against the v1.x branch. Should be ready to go now 🚀

[HofmannZ]

@kmjennison - It's this going to be included in a canary build? 🔜

[kmjennison]

@HofmannZ Yes, just released. Thanks!