* Resolve RTX pair via OnTrack also.
In simulcast probing path, the interceptor chain is not invoked
for primary stream. Not sure if this is a recent change. Due to this,
the RTX pair does not get resolved.
Use the onTrack callback to resolve the pair.
* remove debug
* Refactor receiver and buffer into Base and higher layer.
To be able to share code/functionality with relay.
* WIP
* WIP
* WIP
* WIP
* WIP
* WIP
* WIP
* WIP
* clean up
* deps
* fix test
* fix test
* Don't wait rtp packet to fire track
Create track from sdp instead of first rtp packet,
it is consistent with the browser behavior and
will accelerate the track publication.
* fix test