There could be a race condition where the local getDisplayMedia stream ends
(eg via Chrome`s stop sharing toast) while the broker hasn't finished starting.
That would lead to a scenario where the broker wouldn't emit an end event,
causing screen sharing to be flagged as started with a blank/invalid stream.
Moved bbb-webrtc-sfu utilitaries to properly named folder
Logging improvements to base broker
Added onerror/onstart/onended callback interfaces to base broker