Merge pull request #2 from flutter-webrtc/datachannel-id

RTCDataChannel missing properties

Author: hiroshihorie

lib/src/rtc_data_channel.dart

@@ -70,9 +70,14 @@ abstract class RTCDataChannel {
   /// Get current state.
   RTCDataChannelState? get state;
 
+  /// Get channel id
+  String? get id;
+
   /// Get channel label
   String? get label;
 
+  int? get bufferedAmount;
+
   /// Stream of state change events. Emits the new state on change.
   /// Closes when the [RTCDataChannel] is closed.
   late Stream<RTCDataChannelState> stateChangeStream;