Previously, events from accountsservice would be used to change the
state of the AdwNavigation in ways that don't correspond to the event
that happened. For example, deleting an account would pop the top page
off the stack, even if that page didn't belong to that account.
Especially buggy is the behavior of replacing the currently visible page
with the contents of an account that just changed. systemd-homed changes
the user record whenever authentication happens successfully. So, user
Foo might be trying to edit user Bar, type in their password at the
polkit prompt, and end up looking at a broken version of their own
settings page again: the title would be "Bar", there'd be no list of
users, and hitting the back button would take Foo back to the same
settings page they're currently looking at.
This commits refactors the handling of the accountsservice signals to
fix all the bugs
Fixes https://gitlab.gnome.org/GNOME/gnome-control-center/-/issues/2911
87a62a7c4a