Replace VideoSendStream::Config with new rtclog::StreamConfig in RtcEventLog.

BUG=webrtc:7538

Review-Url: https://codereview.webrtc.org/2857933002
Cr-Original-Commit-Position: refs/heads/master@{#18221}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: c0876aab46356cb4a6ead71b2605301dfce31619
12 files changed