feat: add publishing & audio to ffi (#46)

- Divide FFI protocol into multiple files
- Audio support
- AV Streams/Sources
- Create tracks
- Use Dashmap to store handles
- Add a capture test
     - Ignored by GHA atm

livekit-ffi/build.rs

@@ -1,7 +1,17 @@
 use std::io::Result;
 
 fn main() -> Result<()> {
-    prost_build::compile_protos(&["protocol/ffi.proto"], &["protocol/"])?;
+    prost_build::compile_protos(
+        &[
+            "protocol/ffi.proto",
+            "protocol/handle.proto",
+            "protocol/room.proto",
+            "protocol/track.proto",
+            "protocol/participant.proto",
+            "protocol/video_frame.proto",
+            "protocol/audio_frame.proto",
+        ],
+        &["protocol/"],
+    )?;
     Ok(())
 }
-