* 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

* feat(multi-stream-support) Add screenshare as a second video track to the call.
This feature is behind a sendMultipleVideoStreams config.js flag. sourceNameSignaling flag also needs to enabled. Sending multiple tracks is currently supported only on endpoints running in unified plan mode. However, clients with source-name signaling enabled and running in plan-b can still receive multiple streams .

* squash: check if there is an existing track before adding camera/desktop

* squash: enable multi-stream only on unified plan endpoints.

* add button state / helper dialog

* new audio screen share flow

* change error message

* address a couple of merge conflicts

* fix lint

* address code review

* address code review

* restrict audio screen share on mobile browsers

* feat: Change the screenshare capture fps from UI.
Add the ability to change the capture frame rate for screenshare from the UI. The fps becomes effective only on screen shares that are started after the setting is changed.

* squash: add missing JSDOCs and translations for frames-per-second.

* audio only screen share implementation

* clean up

* handle stop screen share from chrome window

* update icon