Allow vertical orientation for the userWidget so that the user-avatar
can be centered and user's name can be placed below it. The plan
for 3.36 is to use this vertical userWidget layout for both lock
and login screen.
The userWidget is also used while creating the user-selection list
at the login, hence we still need to keep the horizontal layout
for userWidget in place.
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/922
Since the caps-lock warning adds a lot of spacing to dialogs and the
lock screen, hide it by default and only show it when necessary. To make
the transition smooth instead of just showing the label, animate it in
using the height and opacity.
Also add some bottom padding to the label so we can show or hide that
padding, too.
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/952
