[16.0][ADD] auth_oauth_signup

[mlaitinen]

Enable sign up for users logging in using OAuth2 on a per-provider basis, overriding the global setting.

Without this module, your options are:

1. allow sign up for everyone who can access the login page
2. import users (and provide values for oauth_provider_id and oauth_uid) before they log in for the first time.

[jaenbox]

In the event that the variable 'provider' has the value 'false,' the exception error is not caught, and the error is not displayed.
You can fix it with this code. if provider and provider.allow_signup:

[mlaitinen]

In the event that the variable 'provider' has the value 'false,' the exception error is not caught, and the error is not displayed. You can fix it with this code. if provider and provider.allow_signup:

Well spotted, thanks. I fixed it and added a test to make sure that SignupError gets raised when sign up fails and provider is False.

[jaenbox]

LGTM Functional Review

[github-actions]

There hasn't been any activity on this pull request in the past 4 months, so it has been marked as stale and it will be closed automatically if no further activity occurs in the next 30 days.
If you want this PR to never become stale, please ask a PSC member to apply the "no stale" label.