Nov3 Notifications Enhancements

Added Navigation Path and removed isPresentingNotifications from all views.
Simplified and fixed minor UI issues.
Added empty overlay for when there are no notifications
Mark as Read only shows up when >0 unread notifications.
(Not featured in PR: Updated and fixed Firestore rules that were causing updates not to work and inability to delete notifications).

This branch was built off of the latest Notifications_for_Comments branch so I can confirm functionality is working.

lammylol / Flock