Control client button control

[linguini1]

NuttX implementation requires callbacks on GPIO events to send messages over the network. Falling edge = on/arm command, rising edge = off/disarm command. This will be similar to using GPIO for actuators but we're registering interrupt callbacks on them instead. Might need to use work queues since networking will be too much latency in an interrupt handler.

Could be implemented using button driver framework which delivers a signal to the program. Read the example code (not this docs page, it's in examples/buttons): https://nuttx.apache.org/docs/latest/applications/examples/buttons/index.html