Enabling 'gn check' on all //webrtc/modules

We can now use a wildcard and enable 'gn check' on
all the targets in '//webrtc/modules'.

Things are changed a lot since [1] and a refactoring [2]
done by Edward has fixed the problem.

We can now close [1] and enable 'gn check' on all the
targets under '//webrtc/modules'.

[1] - https://codereview.webrtc.org/2609443003/
[2] - https://chromium.googlesource.com/external/webrtc/+/9cbb0a16e5a02538dc9cb18ec9d447e2d2058ec

BUG=webrtc:6828
NOTRY=True

Review-Url: https://codereview.webrtc.org/2732423002
Cr-Commit-Position: refs/heads/master@{#17103}
diff --git a/.gn b/.gn
index 3d3776c..4b2edf0 100644
--- a/.gn
+++ b/.gn
@@ -29,22 +29,7 @@
   "//webrtc/common_audio/*",
   "//webrtc/examples/*",
   "//webrtc/media/*",
-  "//webrtc/modules/audio_coding/*",
-  "//webrtc/modules/audio_conference_mixer/*",
-  "//webrtc/modules/audio_device/*",
-  "//webrtc/modules/audio_mixer/*",
-  "//webrtc/modules/audio_processing/*",
-  "//webrtc/modules/bitrate_controller/*",
-  "//webrtc/modules/congestion_controller/*",
-  "//webrtc/modules/desktop_capture/*",
-  "//webrtc/modules/media_file/*",
-  "//webrtc/modules/pacing/*",
-  "//webrtc/modules/rtp_rtcp/*",
-  "//webrtc/modules/utility/*",
-  "//webrtc/modules/video_capture/*",
-  "//webrtc/modules/video_coding/*",
-  "//webrtc/modules/video_processing/*",
-  "//webrtc/modules/remote_bitrate_estimator/*",
+  "//webrtc/modules/*",
   "//webrtc/stats/*",
   "//webrtc/voice_engine/*",
 ]