Add support for Ethernet using WIZNET

[daveythacher]

This would likely only be used for displays without PWM. This would likely not need brightness correction, gamma correction, CIE1931, dot correct, etc. Just simple on/off for basic message using 8 colors.

Use this code base: https://github.com/daveythacher/RP2040-HAT-C

Logic looks compatible. However it will need the interrupts to be adjusted. It looks like it uses timer alarm interrupts and IO bank 0 interrupt. SPI and DMA are blocking. I think I may promote the core 0 interrupt for this and let the ones used by this code base run as needed. More than likely they are not critical.

[daveythacher]

Note hardware for this will likely be using W5500 breakout and RPI PICO.

[daveythacher]

Actually use this: https://github.com/daveythacher/io6Library

[daveythacher]

I think the W6100 would be better. It supports IPv6