chore: decrease goroutine used in core tunnel

constant/tunnel.go

@@ -0,0 +1,10 @@
+package constant
+
+type Tunnel interface {
+	// HandleTCPConn will handle a tcp connection blocking
+	HandleTCPConn(connCtx ConnContext)
+	// HandleUDPPacket will handle a udp packet nonblocking
+	HandleUDPPacket(packet PacketAdapter)
+	// NatTable return nat table
+	NatTable() NatTable
+}