Adds a check for changing an existing guest user's role before
calling do_update_user in the case that a realm has a current
paid plan with manual license management.
Allowing any admins to create arbitrary users is not ideal because it
can lead to abuse issues. We should require something stronger that
requires the server operator's approval and thus we add a new
can_create_users permission.
We replace knight command with change_user_role command which
allows us to change role of a user to owner, admins, member and
guest. We can also give/revoke api_super_user permission using
this command.
Tweaked by tabbott to improve the logging output and update documentation.
Fixes#16586.
Lauryn Menard
Anders Kaseorg
Mateusz Mandera
Tim Abbott
sahil839