Move congestion controller to a separate module.

This allows other projects to more easily depend on this.

The plan is to move remote_bitrate_estimator and bitrate_controller into this module and reduce the exposed interface to only a simplified version of congestion_controller.h.

No functional changes in this CL.

R=mflodman@webrtc.org, pbos@webrtc.org

Review URL: https://codereview.webrtc.org/1718473002 .

Cr-Commit-Position: refs/heads/master@{#11718}
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 011e3af..e206e40 100755
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -21,6 +21,7 @@
   'webrtc/common_video',
   'webrtc/examples',
   'webrtc/modules/bitrate_controller',
+  'webrtc/modules/congestion_controller',
   'webrtc/modules/pacing',
   'webrtc/modules/remote_bitrate_estimator',
   'webrtc/modules/rtp_rtcp',
@@ -61,6 +62,7 @@
   'webrtc/modules/audio_device/include',
   'webrtc/modules/audio_processing/include',
   'webrtc/modules/bitrate_controller/include',
+  'webrtc/modules/congestion_controller/include',
   'webrtc/modules/include',
   'webrtc/modules/remote_bitrate_estimator/include',
   'webrtc/modules/rtp_rtcp/include',