Split iOS sdk in to separate targets

This CL splits the iOS sdk into separate static libraries for video,
audio, ui, common, and peerconnection-related code. This will in the
future make it easier to compile WebRTC without unneeded components.

BUG=webrtc:4867

Review-Url: https://codereview.webrtc.org/2862543002
Cr-Commit-Position: refs/heads/master@{#18166}

webrtc/modules/video_coding/BUILD.gn

@@ -376,7 +376,7 @@ if (rtc_include_tests) {
     if (is_ios || is_mac) {
       deps += [
         "../../media:rtc_media_base",
-        "../../sdk:webrtc_h264_video_toolbox",
+        "../../sdk:objc_videotoolbox",
       ]
     }
   }

webrtc/modules/video_coding/codecs/test/videoprocessor_integrationtest.h

@@ -23,8 +23,8 @@
 #include "webrtc/sdk/android/src/jni/androidmediadecoder_jni.h"
 #include "webrtc/sdk/android/src/jni/androidmediaencoder_jni.h"
 #elif defined(WEBRTC_IOS)
-#include "webrtc/sdk/objc/Framework/Classes/h264_video_toolbox_decoder.h"
-#include "webrtc/sdk/objc/Framework/Classes/h264_video_toolbox_encoder.h"
+#include "webrtc/sdk/objc/Framework/Classes/VideoToolbox/decoder.h"
+#include "webrtc/sdk/objc/Framework/Classes/VideoToolbox/encoder.h"
 #endif
 
 #include "webrtc/base/checks.h"