Attempt a potential workaround for stuck notifs (#3384)
* Attempt a potential workaround for stuck notifs
* Remove TODOs
* Fix backwards logic about server support for MSC3981 in fetchEditsWhereNeeded
* Check for lack of MSC3981 server support before calling insertEventIntoTimeline
* If no parent event is found, insert purely based on timestamp
* Mark temporary methods as internal
