Extract role assignments from claims

Add a UserRoleAssigner implementation that extract role names from the
users' claims and creates role assignments in the settings service based
on a configured mapping of claim values to ocis role names.

Closes: #5669
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f