Add endpoint to log out all users and disable login #749
Description
This is a feature that would be only available to admins.
Related to #748
The "mass logout" should:
- completely destroy all sessions in redis
- should call keycloak and gitlab to invalidate the sessions that users have there (if this is skipped then logging back in will not require users to provide credentials if they have logged in recently and from the same browser)
When login is disabled it should affect everyone except for admins. Admins should always be able to log in.
It is not clear in the description but these should be two different endpoints.