RtpTransceiver bindings & requirements for publishing tracks (#39)

- RtpSender
- RtpReceiver
- RtpTransceiver
- RtpParameters
- VideoFrameBuilder
- Interior mutability on c++ side
- Cleanup bindings ( Use #pragma once instead of include guards )
     - webrtc-sys/src/* headers are now used in only one place 
     - Avoid confusion between generated headers and our headers
- AdaptedVideoTrackSource
- Cleanup the workaround with unsupported Vec<Shared<T>>
    - Put everything inside one file

webrtc-sys/src/rtp_receiver.cpp

@@ -4,13 +4,48 @@
 
 #include "livekit/rtp_receiver.h"
 
+#include "absl/types/optional.h"
+
 namespace livekit {
+
 RtpReceiver::RtpReceiver(
     rtc::scoped_refptr<webrtc::RtpReceiverInterface> receiver)
     : receiver_(std::move(receiver)) {}
 
-std::unique_ptr<MediaStreamTrack> RtpReceiver::track() const {
+std::shared_ptr<MediaStreamTrack> RtpReceiver::track() const {
   return MediaStreamTrack::from(receiver_->track());
 }
 
-}  // namespace livekit
+rust::Vec<rust::String> RtpReceiver::stream_ids() const {
+  rust::Vec<rust::String> rust;
+  for (auto id : receiver_->stream_ids())
+    rust.push_back(id);
+  return rust;
+}
+
+rust::Vec<MediaStreamPtr> RtpReceiver::streams() const {
+  rust::Vec<MediaStreamPtr> rust;
+  for (auto stream : receiver_->streams())
+    rust.push_back(MediaStreamPtr{std::make_shared<MediaStream>(stream)});
+  return rust;
+}
+
+MediaType RtpReceiver::media_type() const {
+  return static_cast<MediaType>(receiver_->media_type());
+}
+
+rust::String RtpReceiver::id() const {
+  return receiver_->id();
+}
+
+RtpParameters RtpReceiver::get_parameters() const {
+  return to_rust_rtp_parameters(receiver_->GetParameters());
+}
+
+void RtpReceiver::set_jitter_buffer_minimum_delay(bool is_some,
+                                                  double delay_seconds) const {
+  receiver_->SetJitterBufferMinimumDelay(
+      is_some ? absl::make_optional(delay_seconds) : absl::nullopt);
+}
+
+}  // namespace livekit