Media recorder support for iOS/OSX

[rostopira]

[rostopira]

Change to interface should be merged before this PR https://github.com/flutter-webrtc/webrtc-interface/pull/13

[rostopira]

Well, alternative solution for recording audio should be possible. But only if we expose setAudioDeviceModule: method of RTCPeerConnectionFactoryBuilder (src here) But it uses C++ interface. In other words, some changes would be required in WebRTC sdk. Would be cool if we make some ability to apply patches for webrtc before build. Or maybe it's possible to include all headers (including private and c++) in the framework itself?

[rostopira]

Nevermind, I've found where you apply patches I will try to create patch later