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

livekit-webrtc/src/rtp_sender.rs

@@ -0,0 +1,81 @@
+use crate::media_stream::{MediaStream, MediaStreamTrackHandle};
+use crate::prelude::*;
+use crate::rtp_parameters::{RtpEncodingParameters, RtpParameters};
+use cxx::SharedPtr;
+use std::fmt::{Debug, Formatter};
+use webrtc_sys::rtp_sender as sys_rs;
+use webrtc_sys::webrtc as sys_webrtc;
+
+pub use sys_webrtc::ffi::MediaType;
+
+#[derive(Clone)]
+pub struct RtpSender {
+    cxx_handle: SharedPtr<sys_rs::ffi::RtpSender>,
+}
+
+impl Debug for RtpSender {
+    fn fmt(&self, f: &mut Formatter) -> std::fmt::Result {
+        f.debug_struct("RtpSender")
+            .field("track", &self.track())
+            .field("media_type", &self.media_type())
+            .field("ssrc", &self.ssrc())
+            .field("id", &self.id())
+            .finish()
+    }
+}
+
+impl RtpSender {
+    pub(crate) fn new(cxx_handle: SharedPtr<sys_rs::ffi::RtpSender>) -> Self {
+        Self { cxx_handle }
+    }
+
+    pub(crate) fn cxx_handle(&self) -> SharedPtr<sys_rs::ffi::RtpSender> {
+        self.cxx_handle.clone()
+    }
+
+    pub fn set_track(&self, track: MediaStreamTrackHandle) -> bool {
+        self.cxx_handle.set_track(track.cxx_handle())
+    }
+
+    pub fn track(&self) -> MediaStreamTrackHandle {
+        MediaStreamTrackHandle::new(self.cxx_handle.track())
+    }
+
+    pub fn ssrc(&self) -> u32 {
+        self.cxx_handle.ssrc()
+    }
+
+    pub fn media_type(&self) -> MediaType {
+        self.cxx_handle.media_type()
+    }
+
+    pub fn id(&self) -> String {
+        self.cxx_handle.id()
+    }
+
+    pub fn stream_ids(&self) -> Vec<String> {
+        self.cxx_handle.stream_ids()
+    }
+
+    pub fn set_streams(&self, stream_ids: &Vec<String>) {
+        self.cxx_handle.set_streams(stream_ids);
+    }
+
+    pub fn init_send_encodings(&self) -> Vec<RtpEncodingParameters> {
+        self.cxx_handle
+            .init_send_encodings()
+            .into_iter()
+            .map(Into::into)
+            .collect()
+    }
+
+    pub fn parameters(&self) -> RtpParameters {
+        self.cxx_handle.get_parameters().into()
+    }
+
+    pub fn set_parameters(&self, params: RtpParameters) -> Result<(), RTCError> {
+        self.cxx_handle
+            .set_parameters(params.into())
+            .map_err(|e| unsafe { RTCError::from(e.what()) })
+    }
+}