* fix(multi-stream) update selector to find ss track by videoType or mediaType
* ref(multi-stream) move fake ss creation logic and support video type changed
* refactor(multi-stream) decouple sending and receiving multiple screenshare streams
* fix(multi-stream) fix receiver constraints with signaling and without multi-stream
* fix(mutli-stream) ensure plan b original SS thumbnail displays avatar
* fix(multi-stream) show fake SS for plan b sender
* refactor(multi-stream) poc for moving SS creation to state listener
* remove reference to fake SS creation
* fix lint errors
* rename to virtual screenshare participants
* fix minor bugs
* rename participant subscriber to specify web support only
Jaya Allamsetty
William Liang