Proper Arduino Support

[securelyfitz]

Low priority, since you can just use can just use pico or generic and setTX/setRX:
https://arduino-pico.readthedocs.io/en/latest/serial.html

arduino pins are set in /home/joefitz/.arduino15/packages/rp2040/hardware/rp2040/4.3.1/variants/rpipico/pins_arduino.h

[securelyfitz]

even lower priority if we name pins in a non-arduino-friendly method