Move the SetRTPTimestamp method from TransformableAudioFrameInterface to the base class, so that RTPTimestamps can also be modified on encoded video frames. Bug: webrtc:14709 Change-Id: I355be527c2be201c9201e04c431394c962237140 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/310781 Commit-Queue: Tony Herre <herre@google.com> Reviewed-by: Harald Alvestrand <hta@webrtc.org> Reviewed-by: Palak Agarwal <agpalak@google.com> Cr-Commit-Position: refs/heads/main@{#40378}