Micropython on Wiznet

I've submitted a patch to micropython which provides full support for both the W5100S-EVB-Pico or a regular pico board with the Wiznet Ethernet Hat.This PR has gone through a lot testing and a few iterations of implementation - with a number of reviews and discussions with the micropython maintainer, @dpgeorge.The PR is in its expected final form, with full unit test suite passing and stable performance tests - with room for future improvements. I've already got a work-in-progress update to use receive interrupts to improve speed, however it will require further work for ensure no interrupt context issues.Once the current PR is accepted (hopefully within the next couple of days), automatically updated releases of micropython firmware this hardware will be forever available on https://micropython.org/download/?port=rp2 ready for people to download and flash to their new boards to use the easy-to-use micropython platform with reliable ethernet networking from Wiznet.