OIDC Support

### Description

This feature would allow users to be authenticated via an external OIDC server rather than the built in authenticator. This would be very helpful for those looking to better integrate glance into their SSO homelabs. While it is possible to simply host glance behind an external auth provider, I believe this would pair very nicely with #858, allowing different OIDC users or groups to have access to different pages.

I am happy to implement this feature myself, and I should only need to add one library to handle talking to the server