Auth0 Integration V2

[aidenprice]

Hi again,

This is the cleaned up PR from the previous attempt, please ignore my earlier PR and consider this one instead. Sorry for the messy git history.

This PR adds Auth0 OAuth integration following the same pattern as Okta. The key names are different enough to justify a different handler.

Thank you again,
Aiden

[jczhong84]

@aidenprice thanks for the PR to add Auth0.
Looks like it's mostly same as okta except the get_auth0_urls. Maybe we can just inherit it from OktaLoginManager, rename get_okta_urls as get_oauth_urls and override it for Auth0LoginManager

btw as I know, auth0 and okta are the same company now.

[aidenprice]

Hi, I've tried your suggestion and it certainly cleans up a lot of repeated code.
One thing I should point out though, the LOG = get_logger(__file__) isn't inheritable or injectable. So when you instantiate an Auth0LoginManager it will represent logs as coming from the Okta file.

[aidenprice]

Thank you!