off-board Prusa Connect server for Prusa MINI

Because of https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/1285, I wanted to have the actual prusa WUI running off the printer, but still getting its data from the printer API. This little go file does the trick.

Since this makes use of the GPLv3 WUI code, I hereby license this under that as well.

main.js and main.css are taken from the 4.3.4 release.