Moving iOS Audio Device to sdk.

This change forks the existing iOS audio device module and audio device
from modules/audio_device/ into sdk/objc/Framework. It also updates
RTCPeerConnectionFactory to use the forked implementation.

The unit tests are re-implemented as XCTests.

(was: https://webrtc-review.googlesource.com/c/src/+/67300)

Bug: webrtc:9120
Change-Id: I07340505137b16c2dd487569ad0112f984557bba
Reviewed-on: https://webrtc-review.googlesource.com/75125
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Commit-Queue: Peter Hanspers <peterhanspers@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23208}

sdk/objc/Framework/Classes/PeerConnection/RTCPeerConnectionFactory.mm

@@ -38,6 +38,10 @@
 #include "sdk/objc/Framework/Native/src/objc_video_encoder_factory.h"
 #endif
 
+#if defined(WEBRTC_IOS)
+#import "sdk/objc/Framework/Native/api/audio_device_module.h"
+#endif
+
 // Adding the nogncheck to disable the including header check.
 // The no-media version PeerConnectionFactory doesn't depend on media related
 // C++ target.
@@ -55,6 +59,14 @@
 
 @synthesize nativeFactory = _nativeFactory;
 
+- (rtc::scoped_refptr<webrtc::AudioDeviceModule>)audioDeviceModule {
+#if defined(WEBRTC_IOS)
+  return webrtc::CreateAudioDeviceModule();
+#else
+  return nullptr;
+#endif
+}
+
 - (instancetype)init {
 #ifdef HAVE_NO_MEDIA
   return [self initWithNoMedia];
@@ -65,7 +77,7 @@
                                                      [[RTCVideoEncoderFactoryH264 alloc] init])
                        nativeVideoDecoderFactory:webrtc::ObjCToNativeVideoDecoderFactory(
                                                      [[RTCVideoDecoderFactoryH264 alloc] init])
-                               audioDeviceModule:nullptr
+                               audioDeviceModule:[self audioDeviceModule]
                            audioProcessingModule:nullptr];
 #endif
 }
@@ -87,7 +99,7 @@
                        nativeAudioDecoderFactory:webrtc::CreateBuiltinAudioDecoderFactory()
                        nativeVideoEncoderFactory:std::move(native_encoder_factory)
                        nativeVideoDecoderFactory:std::move(native_decoder_factory)
-                               audioDeviceModule:nullptr
+                               audioDeviceModule:[self audioDeviceModule]
                            audioProcessingModule:nullptr];
 #endif
 }