Add datachannel c apis and callbacks(#3328)

增加datachannel数据收发的回调通知 #3326，和控制datachannel回显的开关

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Co-authored-by: xiongziliang <771730766@qq.com>

src/Common/config.cpp

@@ -58,6 +58,12 @@ const string kBroadcastStreamNoneReader = "kBroadcastStreamNoneReader";
 const string kBroadcastHttpBeforeAccess = "kBroadcastHttpBeforeAccess";
 const string kBroadcastSendRtpStopped = "kBroadcastSendRtpStopped";
 const string kBroadcastRtpServerTimeout = "kBroadcastRtpServerTimeout";
+const string kBroadcastRtcSctpConnecting = "kBroadcastRtcSctpConnecting";
+const string kBroadcastRtcSctpConnected = "kBroadcastRtcSctpConnected";
+const string kBroadcastRtcSctpFailed = "kBroadcastRtcSctpFailed";
+const string kBroadcastRtcSctpClosed = "kBroadcastRtcSctpClosed";
+const string kBroadcastRtcSctpSend = "kBroadcastRtcSctpSend";
+const string kBroadcastRtcSctpReceived = "kBroadcastRtcSctpReceived";
 
 } // namespace Broadcast