feat: video publishing (#42)

- Prepare webrtc abstraction ( for future wasm support )
- Added track publish support for videos
  - Added LogoTrack example to simple_room demo
- Lot of cleanup
- There are compiler warnings I'll solve on our v1 release

webrtc-sys/include/livekit/jsep.h

@@ -65,6 +65,7 @@ class SessionDescription {
   explicit SessionDescription(
       std::unique_ptr<webrtc::SessionDescriptionInterface> session_description);
 
+  SdpType sdp_type() const;
   rust::String stringify() const;
   std::unique_ptr<SessionDescription> clone() const;
   std::unique_ptr<webrtc::SessionDescriptionInterface> release();