These changes make the navigation and status bar accessible from within fullscreen applications by allowing the user to tap on the top or tap or drag on the bottom of the screen.
Also, since the top panel is now over top of all fullscreen applications, this moves the action drawer swipe area back into the status bar.

The drawer was recently updated where it is now technically always is visible. So we need to update the binding for MobileShellState to use drawer.intendedToBeVisible so that it works properly.
This merge request implements a more mobile optimized solution for popup notification.
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The current controls are:
- Swipe up to move the notification to the notification center.
- Swipe left/right to dismiss the notification entirely.
- If multiple popup notifications are grouped together, tap on the bottom area to view them in a expanded view.
What still needs to be done:
- ~~For notification without a default action, tapping on them should probably open up the associated app.~~ Note: I think I will add this in a separate merge request as it probably should be the case regardless if the notification is a popup
- ~~Swiping down on a notification currently does nothing. Maybe we should map this to a notification action?~~ Note: I have some ideas I will try later, though for now, I will leave this action blank
- ~~The expanded view of notifications should be able to be dismissed by swiping up/down on the top/bottom of the list.~~ Note: Added
- Investigate further into how to remove the current desktop popup notifications.
- ~~Code clean up.~~ Note: The code is at least a bit better
Single popup notification:

Multiple popup notifications:

Multiple popup notifications in the expanded view:

Any feedback would be greatly appreciated.
Contributes to #317
This refactor changes WindowMaximizedTracker from being a Singleton, and allows for it to be created in a way such that screens can be filtered out.
This fixes external screens from having their homescreen "zoom out" when an app is maximized on another screen.
The eventual goal is to have as few singletons with state as possible in the mobileshell component when it is imported into components such as the lockscreen.
This doesn't fully accomplish it, but moves the audio provider singleton to MobileShellState, which will eventually need to be prevented from importing into non plasmashell processes.
This also disables the sound feedback when changing volume, since it can be a source of lag when showing the applet.