Add WIZnet W55RP20-EVB-Pico board

[wiznet-mason]

The W55RP20 is a SiP chip that integrates the RP2040 with WIZnet's W5500 and 2MB Flash.
https://docs.wiznet.io/Product/ioNIC/W55RP20/overview

[earlephilhower]

Thanks! Looks like you need to check in the modified package/package_pico_index.template.json file (modified/built by makeboards.py per the CI failure.

[maxgerhardt]

@wiznet-mason recheck CI, it's complaining about

/home/runner/arduino_ide/hardware/pico/rp2040/libraries/lwIP_w55rp20/src/wiznet_pio_spi.c:79:23: error: comparison of integer expressions of different signedness: 'int' and 'unsigned int' [-Werror=sign-compare]
   79 |     for (int i = 0; i < count_of(wiznet_pio_spi_state); i++) {
      |                       ^
cc1: all warnings being treated as errors

[earlephilhower]

Ping, @wiznet-mason . We can't edit your repo, so you'll need to fix the CI warnings from gcc (use File->Preferences->Compiler Warnings->All to mimic the -wall -werror we run in CI).

[wiznet-mason]

Thank you very much for all the advice. I’ll try again and commit.

[earlephilhower]

Looks like we're all good now, thanks!

[wiznet-mason]

Thank you very much!

[maxgerhardt]

Aww, the board was not added to the README.md list though!