notifications: Implement popup notifications

This merge request implements a more mobile optimized solution for popup notification.

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.