multi: add unsafedisconnect as a dev config

This commit adds a new dev config `unsafedisconnect` as we sometimes
want to disconnect nodes in our itests.

lncfg/dev.go

@@ -24,6 +24,17 @@ func (d *DevConfig) ChannelReadyWait() time.Duration {
 	return 0
 }
 
+// GetUnsafeDisconnect returns the config value, which is always true for
+// production build.
+//
+// TODO(yy): this is a temporary solution to allow users to reconnect peers to
+// trigger a reestablishiment for the active channels. Once a new dedicated RPC
+// is added to realize that functionality, this function should return false to
+// forbidden disconnecting peers while there are active channels.
+func (d *DevConfig) GetUnsafeDisconnect() bool {
+	return true
+}
+
 // GetReservationTimeout returns the config value for `ReservationTimeout`.
 func (d *DevConfig) GetReservationTimeout() time.Duration {
 	return DefaultReservationTimeout