OAuth: Add auto user registration on first login

[Saph1s]

At this moment (v1.0.0-beta14) there is no solution for auto user registration on login via OAuth (Authentik as example).

It would be nice to have this feature!

[Boy132]

Very unlikely.
Admins still need to assign servers to the user so they can actually do something.

[RMartinOscar]

Could be cool for subusers but its not a must-have.
As for user registration it should be optional (and disabled by default)

[Saph1s]

Very unlikely. Admins still need to assign servers to the user so they can actually do something.

Yeah, I understand that. But you don't need to create user by yourself.
Also, auto role assignment by claims can simplify the process significantly. With auto role assignment based on claims, users can be granted appropriate permissions automatically during the login process, reducing the workload on admins. This approach streamlines user onboarding while still allowing admins to manage server assignments as a separate step when needed.