Add ChannelReceive test for transformed frames

The frame transformer tests only check that Transform() is called. Add a
test that hands the transformed frame back through the registered
callback, and verifies that the audio reaches the output together with
the packet info of the received packet.

Bug: webrtc:11993
Change-Id: Ibe9bcb66b16a0c771ffe17598d4e1b8b72ab09ec
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/507020
Reviewed-by: Erik Språng <sprang@webrtc.org>
Auto-Submit: Tomas Gunnarsson <tommi@webrtc.org>
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#48796}