Add ability to specify if rate controller of video encoder is trusted.

If rate controller is trusted, we disable the frame dropper in the
media optimization module.

This is a re-land of
https://webrtc-review.googlesource.com/c/src/+/105020

Bug: webrtc:9890
Change-Id: I418e47a43a1a98cb2fd5295c03360b954f2288f2
Reviewed-on: https://webrtc-review.googlesource.com/c/109141
Commit-Queue: Erik Språng <sprang@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25570}

modules/video_coding/codecs/vp8/libvpx_vp8_encoder.h

@@ -86,6 +86,7 @@ class LibvpxVp8Encoder : public VideoEncoder {
 
   const absl::optional<std::vector<CpuSpeedExperiment::Config>>
       experimental_cpu_speed_config_arm_;
+  const bool trusted_rate_controller_;
 
   EncodedImageCallback* encoded_complete_callback_;
   VideoCodec codec_;