Enumerating authentication user flows/error handling

[schlich]

Goal: Members should be able to sign in with their existing Auth0 account.

What can go wrong? What happens when users/members/nonmembers visit the page, try to log in, etc.? We should try to minimize custom work here. We just need to make sure we are handling cases like this. A mermaid sequence diagram diagram may be helpful here for communication or organizing thoughts but shouldn't be a priority on its own.

This ticket should ensure that logout covers ActionKit and Auth0.

[erikdstock]

Q: Can we make the auth script check for user groups in auth0 (eg beta_testers) instead of a hard-coded array? cc @emiliadecaudin

[emiliadecaudin]

Yes I think we can do this.