KP3S 18mm inductive probe mount

I remixed wtl00r's version of the probe mount (https://www.thingiverse.com/thing:5621035) to be able to use a LJ18A3-8-Z/BX DC NPN probe (18mm diameter). Use 2 M3 screws and nuts to fix to the KP3S's stock fan guard.

Probe X and Y offset settings (Marlin):

X30, Y2