TypeMatrix_rp2040

RP2040 PCB for TypeMatrix keyboard, to substitute to the default PCB. Usage: upgrade TypeMatrix to QMK firmware.

Should fit into the typematrix without any change, unless:

- 2 holes to perform on the left side of the TypeMatrix black box (to access to BOOT and RESET buttons)

- unsolder / resolder the USB cable - be aware of the D- / D+ cable side

- update some item ref (as resistors), to pick availeble refs at JLCPCB for direct soldering

- in QMK, design the right keyboard matrix (not done yet), to affect GPIO0 to 25 to the right row/col.

TO BE VERIFIED, not yet tested.