Integrate `RttSimulator` into video timing simulator

In this change, the previously landed `RttSimulator` is integrated into
the video timing simulator. The `RtcEventLogDriver` receives the
smoothed session-level RTT estimates, and distributes them to the
streams. The streams use the RTTs to adapt the NACK module (inside the
`Assembler`) and the jitter estimator (inside the `RenderingTracker`).

Bug: b/423646186
Change-Id: I792fcfea7ac7f4bf8d97a73f674a7d5ca8c25727
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/479821
Commit-Queue: Rasmus Brandt <brandtr@webrtc.org>
Reviewed-by: Åsa Persson <asapersson@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#47960}