Move remaining traces of VoiceEngine

- Move files from voice_engine/ to audio/.
- Rename voice_engine/utility.* to remix_resample.* since there are no other
  utilities in those files.
- Move test/mock_voe_channel_proxy.h to audio/.
- Removed voe_channel_id from Audio[Receive|Send]Stream::Config.
- Remove VoiceEngine* from AudioState::Config.
- Fix a few cpplint complaints which showed when moving files.

NOPRESUBMIT=true

Bug: webrtc:4690
Change-Id: Id266c822d956625c358fa5e193e6f4837164aef8
Reviewed-on: https://webrtc-review.googlesource.com/39268
Commit-Queue: Fredrik Solenberg <solenberg@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21657}
diff --git a/audio/audio_send_stream_unittest.cc b/audio/audio_send_stream_unittest.cc
index 4644bf4..925f93e 100644
--- a/audio/audio_send_stream_unittest.cc
+++ b/audio/audio_send_stream_unittest.cc
@@ -15,6 +15,7 @@
 #include "audio/audio_send_stream.h"
 #include "audio/audio_state.h"
 #include "audio/conversion.h"
+#include "audio/mock_voe_channel_proxy.h"
 #include "call/fake_rtp_transport_controller_send.h"
 #include "call/rtp_transport_controller_send_interface.h"
 #include "logging/rtc_event_log/mock/mock_rtc_event_log.h"
@@ -32,7 +33,6 @@
 #include "test/gtest.h"
 #include "test/mock_audio_encoder.h"
 #include "test/mock_audio_encoder_factory.h"
-#include "test/mock_voe_channel_proxy.h"
 
 namespace webrtc {
 namespace test {