feat: 服务端AEC功能

ref: 入口解码为pcm音频数据，vad和asr可直接使用

main/xiaozhi-server/core/handle/helloHandle.py

@@ -56,6 +56,9 @@ async def handleHelloMessage(conn: "ConnectionHandler", msg_json):
             conn.mcp_client = MCPClient()
             # 发送初始化
             asyncio.create_task(send_mcp_initialize_message(conn))
+        if features.get("aec"):
+            conn.logger.bind(tag=TAG).debug("客户端启用了服务端AEC")
+            conn.client_aec = True
 
     await conn.websocket.send(json.dumps(conn.welcome_msg))