Add a command to set LED bit mask

[Juggler00]

I know there has been much discussion about radio-style buttons, LED behaviour and such. I'm wondering if it would be overly difficult to create a separate command to set the LED bit-mask. Currently, there is a command to set individual keypad LEDs. The challenge is that with MQTT, you have to stagger the commands otherwise insteon-mqtt does not consume them before the next one arrives.