Use EncoderSimulcastProxy for all codecs
Use EncoderSimulcastProxy for all codecs

Some codecs don't support directly creating simulcast layers with
non-optimal parameters. This proxy will detect this and create
multiple encoders then, one for each layer as a fallback.

Bug: webrtc:10069
Change-Id: I4bcafcfdd68d9ed466e2fafe564db849de6ed4f6
Reviewed-on: https://webrtc-review.googlesource.com/c/119264
Reviewed-by: Erik Språng <3ab8c90c99d6dd7822e0fad803ab0211dd287ae5@webrtc.org>
Commit-Queue: Florent Castelli <238c27192d78679c9b4e4a6413f53bb164e8bb18@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#26373}
TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc