alfawise u30 upgrade bed leveling sensor

Upgrade for mounting a microswitch sensor to enable automatic bed leveling on the alfawise u30.

This model is made to mount the filament runout sensor that came with the printer and use it as a probe to gather bed leveling data.

Feel free to modify and/or publish a version with the attachment for a different microswitch

This mod possible thanks to marlin firmware on a btt skr mini e3 motherboard, i bought my printer without the original motherboard because it was broken, so i don't know if this mod can be useful in pair with the original one.

For more info fell free to ask.