#779 was happening because environment objects were set on contentView,
which is not the _outmost_ root view. This clarifies why the Theme
object was not being found in ThemeLockScreenModifier.
Also, do not hardcode LogoView as lock view.
- Refactor AppUI initialization in all platforms (sort of template
method pattern)
- Make AppMenu specific to macOS by wrapping it into a folder for
consistency
- Add SizeClassProviding for repeated checks on hsClass/vsClass
Fixes#659
- Let the user close the window, the app will just remain alive in the
status bar
- Accordingly, replace "Confirm quit" preference with the option to stay
alive in the status bar
- Add "About..." item
Split AppUI into AppUI and AppUIMain to allow for a new, simplified
AppUITV target tailored for the Apple TV.
As a PoC, present a view with a list of the shared profiles.
Davide