Add support for Adafruit Feather RP2040 (8MB). Identified with a unique
USB PID so it displays properly once programmed one time. Moved LED to
pin 13 (per the website docs), but have no board to test.
Add over/underclocking menus, applied at boot. Use at your own risk, as
usual.
Add shims to allocate flash space for a filesystem (but not implemented
yet).
Add a "generic" RP2040 board
