Allow modification and display user status in the web interface

[linuspahl]

Description

With #9374 we've implemented the backend code for the user status. Now we need to display the status in the user overview and on the details / edit page. The user overview and also the edit page should contain an action to change this status. This action should only be available for internal users.

With these changes we should also remove the enable / disable buttons form the synced users overview on the authentication details page and the related actions, since they are no longer needed