Configure VoE NACK through AudioReceiveStream::Config, for receive streams. Also minor refactoring of WVoE unit test.

BUG=webrtc:4690

Review-Url: https://codereview.webrtc.org/2060813002
Cr-Original-Commit-Position: refs/heads/master@{#13140}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 8189b02feaae73e542190f79c57e858fd7d84f3d
7 files changed