fix: datachannel deadlocks & dispose crashes (#87)

- Fix datachannel deadlock on dispose
- Fix audio device being disposed on the wrong thread
- Allow multiple RtcRuntime to be created (Useful for unit tests where we use multiple PeerConnectionFactory)

webrtc-sys/include/livekit/webrtc.h

@@ -80,6 +80,8 @@ class RtcRuntime : public std::enable_shared_from_this<RtcRuntime> {
   // have one livekit::VideoTrack associated with it).
   // The only reason we to do that is to allow to add states inside our
   // wrappers (e.g: the sinks_ member inside AudioTrack)
+  // DataChannel and the PeerConnectionFactory don't need to do this (There's no
+  // way to retrieve them after creation)
   webrtc::Mutex mutex_;
   std::vector<std::weak_ptr<MediaStreamTrack>> media_stream_tracks_;
   // We don't have additonal state in RtpReceiver and RtpSender atm..
@@ -87,9 +89,9 @@ class RtcRuntime : public std::enable_shared_from_this<RtcRuntime> {
   // std::vector<std::weak_ptr<RtpSender>> rtp_senders_;
 
 #ifdef WEBRTC_WIN
-  rtc::WinsockInitializer winsock_;
-  rtc::PhysicalSocketServer ss_;
-  rtc::AutoSocketServerThread main_thread_{&ss_};
+  // rtc::WinsockInitializer winsock_;
+  // rtc::PhysicalSocketServer ss_;
+  // rtc::AutoSocketServerThread main_thread_{&ss_};
 #endif
 };