Einsy z-axis frame stabilizer

An attempt to get the left side of the frame to be more stable without going full taurus or bear, thus only making a small addition to the standard prusa mk3.
It will in theory hold the frame more stable in a similar manner as the psu does on the right side.
Needs a small extrusion-mounting-plug, i.e. this one: https://www.thingiverse.com/thing:2866470
It also needs ~2mm longer screws than the standard (M3 x 30 should do it), but these should be included in the spare-part-bag.