Merge changes from topic "200609_ViLTE_sync"

* changes:
  Miscellaneous fixups for VT contribution update.
  VT: ARTPWriter: Introduce Moderator logic
  VT: ARTPWriter: Add traffic recorder
  VT: Migration AAVCAssembler patches to AHEVCAssembler.
  VT: Enhancements on RTP depacketizer (2)
  VT: Refine codes in AAVCAssembler.
  VT: RTCP:NACK implementation. (RFC-4585)
  VT: Report all data about packet receiving up to application
  VT: Enhancements on RTP depacketizer
  VT: Enhancements on RTP packetizer.
  VT: Added an interface to set JitterBufferTime.
  VT: Some parameters not provided to encoder if source is surface.
  VT: H265: prepend VPS/SPS/PPS to I-frame.
  VT: Change to KMP algorithm for searching H.264 start prefix code
  VT: ARTPWriter: StripStartcode() & SpsPpsParser() bug fix
  revert ARTPWriter StripStartcode fix