fix(TPC): Ignore stopped transceivers on FF during new track addition. Firefox lists stopped transceivers when getTranceivers is called, ignore these when picking a trancceiver for a screenshare track. Fixes an issue when starting screenshare fails if there are stopped tranceivers in the peerconnection (i.e., if some remote users with sources have left the call).
fix(TPC): Ignore stopped transceivers on FF during new track addition.
Firefox lists stopped transceivers when getTranceivers is called, ignore these when picking a trancceiver for a screenshare track. Fixes an issue when starting screenshare fails if there are stopped tranceivers in the peerconnection (i.e., if some remote users with sources have left the call).

jitsi/lib-jitsi-meet,jitsi/lib-jitsi-meet