Integrate logging of RTX original sequence number in `Call`.

With this change, we retain centralized logging of incoming packets, at
the cost of having to do RTX decapsulation centrally as well. This was
deemed better than pushing down the logging to the streams (where
decapsulation fits better), due to lower risk for missing to log packets
after future refactorings.

Bug: b/305890678, b/423646186
Change-Id: I0af762925406cdab4cd3eb659662a08d41395929
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/432903
Commit-Queue: Rasmus Brandt <brandtr@webrtc.org>
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#46475}