Some of the fake encoders, FakeVp8Encoder in particular, reuse structures that in turn rely on field trials. Thus fake encoders also can benefit from Environment passed at construction. Bug: webrtc:15860 Change-Id: Ia1542b2663c75fd467e346aad9ead627ff9b3b0f Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/346780 Reviewed-by: Philip Eliasson <philipel@webrtc.org> Commit-Queue: Danil Chapovalov <danilchap@webrtc.org> Reviewed-by: Jeremy Leconte <jleconte@webrtc.org> Cr-Commit-Position: refs/heads/main@{#42046}