default firmware v1.3

[NOTE: This version appears to have issues on Mac OSX that are being worked on]

New release of the default firmware.

• Added an interactive shell on the default UART with help message (no command yet)
• Fixed TinyUSB not letting the board start.
• Added an interface to interact with the SPI bus (doc)

Features: https://github.com/tinyvision-ai-inc/pico-ice/tree/main/Firmware/pico-ice-default

pico_ice_rgb_blink.uf2 is provided for testing the MSC interface.
pico_ice_rgb_blink.bin is provided for testing the DFU interface.
pico_ice_zero.uf2 and pico_ice_zero.bin are there to reset the flash by filling it with 0x00.

See the documentation for installing it onto the pico-ice.