Trinity V1 Bed LEDs

Adds a mounting point for an LED strip under the bed of the Trinity V1, to display progress or errors. Wholly unneeded, but pretty cool, I'd say. It mounts on the bed carrier, using two m3 bolts and lock nuts, instead of the m4 bolts expected. It's made for LED strips ~7.5 mm tall and ~2 mm thick. It's designed to fit 4x3mm magnets (x6), but the tolerances are tight enough you might not need to. While I cannot confirm, I think it will fit the Ender 3 NG.