Every page (after login) has access
to the User object via context.read/watch<User>().
This reduces localstore and asnyc operations,
as the screens do not have to load the user every time.
Additionally this prevents anyone from
using the without a user object.
The screen allows the user to change the default permission set,
that applies to every member (but not the owner nor the admins).
This screen is only accessible by the owner,
admins or members with the changeAdmin permission.