Merging bootloader fork upstream

[gibbz00]

Removes the need to make sure downstream is up-to-date.

• Acquire a separate USB PID and add values to board.h. Possible starting points:
  https://pid.codes/
  https://github.com/openmoko/openmoko-usb-oui
  https://wiki.openmoko.org/wiki/USB_Product_IDs
  added BlueMicro833 openmoko/openmoko-usb-oui#34
  Appropriate values in zmk/app/Kconfig should also be updated.
• Make sure UF2 board name specifications are followed. See: Add mikoto board adafruit/Adafruit_nRF52_Bootloader#230 (comment)
• Fix to-dos and comments in bootloader/src/borne_keyboard/board.h
• Add board to be part of CI/CD pipeline: https://github.com/adafruit/Adafruit_nRF52_Bootloader/blob/master/.github/workflows/githubci.yml
• Squash commits before merge request