* Refactor media track subscriptions
- To enable re-use of common bits
- Add max quality from other nodes
* Lock close handlers slice
* Reverting multiple on close handlers of downtrack, unclear if it is needed yet
* Make Logger a pointer
* audio level in MediaTrack like remote media track
* Cleanup
* Add a no subscribers callback
* Add method to update subscribed quality from another node
* loss proxying from remote node
* Address comments from David
* create subscriber node quality map