FR: Allow config of wifi from touchscreen

[knw257]

I've converted my Neptune 4 Plus to OpenNept4une and installed the display connector, but one thing I noticed is that I cannot configure the basic wifi settings via the touchscreen like I can on the stock firmware. I understand that, after initial install, it has to be done via terminal (either serial or SSH via ethernet), but once the installation is completed, I'd like to be able to change the wifi network info via the touchscreen. I've been looking through the code, but it's a little over my head. I think we'd need something to show the WLAN page, and something to handle the alphanumeric input, neither of which appear to be implemented. I wish Elegoo would make the source code of znp_tjc_klipper available, but I can't find that anywhere to see how they implemented this.

If anyone could help implement this feature in this package, it would be greatly appreciated.