Add the possibility for Admin user to control user's notifications

Currently only the user itself can see the notifications in the user profile.
As an Admin user there is the need to fully manage the settings from the user profile, including the notifications.
If for example the user sheet is edited in order to display the notification tab, the notifications of the current logged user are displayed not the notifications of the notifications of the users that is moderated.
As far as I tested the notification system is using the preferences of the context user (ie the user currently being logged-in) and not doc user from the profile.