XT90 clamshell strain relief cover cord grip

This is a remix of https://makerworld.com/en/models/1740967-xt90-cover-enclosure#profileId-1850207

I modified the cable exit to be round for smaller gauge cables.  The round cable exit diameter can be adjusted using the parameters.  There is a set of holes to ziptie the cable for strain relief.

I changed the two screw holes that clamp the two halves together to just one hole that uses an M3 threaded insert and M3 screw.