Support for wireless keyboards

[tnibler]

Putting this here mostly as a note, I'm ready to work on everything listed once I have time from April onwards. In the meantime if anyone is interested, feel free :-)

• Interface PCB: probably just a generic one with Pro Micro footprint for nrf52840 boards since they're easy to get now.
  • power switch: find a good one that's widely available that can reach through a few mm of shell. Maybe inset the shell a bit
  • battery connector/pads
  • Reset button: maybe possible to make it pressable through the case or bottom plate, would be very nice (sort of annoying with many other designs).
• Port Cutouts: make them configurable so both halves can have any of USB/TRRS (done)
• Battery holder: just a flat piece of plastic with zip tie holes somewhere inside the case