[tracking] Engaging Notification

[gnunicorn]

• HTML tags show up in Android Notifications
• Notifications failure tracking plan #2451
• Document different Notification types and their expectations #2447
• When clicking on Chat notifications on Android, the chat opens twice, chat some times can't be interacted with
• Notifications seem to not always make it to the clients
• Notifications appear double on Linux Desktop
• Upon click of Notification of a boost doesn't go to the boost #2448
• Notifications don't show any content on iOS #2449
• Design how Notifications for Comments should work
• Confirm that we have the same parameters as other clients use #2450
  like Element-X or Fluffy Chat have to ensure we don't miss any important parameters in the way to ensure notifications are visible.
• Tracing Notifications on the Backend #2452
  and ideally all the way to the client to make sure we are not loosing them somewhere there before they even make it to the server

Adjacent (not directly about the Push Notification code itself but similar to the user)

• Users can't find Chat Invitations #2453
• Users have a hard time to make out what the notifications was about when it links them wrong (or they swiped it away) #2454