Delete the deprecated IncomingPacket method, and convert implementation
to use RtpPacketReceived rather than RTPHeader.
Part 1 was https://webrtc-review.googlesource.com/c/src/+/100104
Bug: webrtc:7135, webrtc:8016
Change-Id: Ib4840d947870403deea2f9067f847e4b0f182479
Reviewed-on: https://webrtc-review.googlesource.com/c/6762
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25648}