feature_request(auth): alternative authentication methods

[Kristinita]

1. Summary

It would be nice, if would be possible authenticate in Wildfire, use alternative authentication methods, supported by Firebase.

2. Argumentation

1. Simplicity. Press to button Sign up via GitHub simply, that print e-mail and password.
2. Spam preventing. At the time for Wildfire authentication even e-mail verification code not needed. Spammers needs merely fill authentication areas and post spam comments. Wildfire needs more spam protection.
3. Data privacy. Firebase console admins can see users e-mails. Perhaps some users do not want show e-mail addresses, and we must respect their opinion.

3. Example of expected behavior

Site owner visit Firebase Console → Authentication → enable, for example, GitHub and Google.

Users can authenticate via GitHub and Google, not via e-mail solely.

Thanks.