enhance the keyboard constant detection

[LennartHennigs]

• parse key definition upon load
• send errors to console (see be able to send strings from the keypad to the console output via watchdog #6 )
• allow alternative key names (OPTION, CONTROL, ...)
  • CMD = GUI
  • OPTION = LEFT_ALT

Resource

• see: https://docs.circuitpython.org/projects/hid/en/latest/api.html