[Feature] Long-press GPIO buttons to activate different functions

[roryaronson]

This would double the user-programmable functions with the same hardware.

Some ideas:

• The red button could be long-pressed to shutdown the bot. Momentary pressing it would still e-stop the bot.
• The yellow button could be long-pressed to reboot the bot. Momentary pressing it would still unlock the bot.
• A button could be programmed to mount a tool on momentary press, and put that tool away on long-press.