Update mounting holes and nut seats to match M4 hardware dimensions

[EfficiencyJunky]

We want to test if M4 hardware works better than the previous 10-32 hardware for mounting bolts

Things to adjust:

1. Mounting Bolt hole diameter -> 4mm
2. Mounting Bolt Head Diameter -> 8mm + Gap
3. Mounting Nut Width -> 7mm
4. Mounting Nut Depth -> 3.2mm + Gap
5. D-Ring clearance -> drop the height of the outer shell from 1mm to 0.2mm -> Add 2mm fillet to inside lip

[EfficiencyJunky]

10-32 Bolt and nut dimensions:
10-32 Bolt Diameter: 0.19 inch -> mounting_bolt_diameter
10-32 Clearance hole diameter: 5mm -> mounting_bolt_clearance_hole_diameter_10_32
10-32 Nut width: 8mm -> nut_10_32_width
10-32 Nut height: 2.8mm -> nut_10_32_height
10-32 Bolt Head Diameter: 9.5mm -> mounting_bolt_head_diameter
Thickness of plastic from d-ring cutout to head hole == 1mm

M4 Bolt and nut dimensions:
Bolt: https://www.mcmaster.com/92005A242/
Nut: https://www.mcmaster.com/91828A231/

M4 Bolt Diameter: 4mm (3.8mm measured)
M4 Clearance hole diameter: 4mm -> M4_mounting_bolt_clearance_hole_diameter
M4 Nut width: 7mm -> M4_mounting_nut_width
M4 Nut height: 3.2mm -> M4_mounting_nut_height
M4 Bolt Head Diameter: 8mm -> M4_mounting_bolt_head_diameter
Thickness of plastic from d-ring cutout to head hole == 1.8mm

[EfficiencyJunky]

TOP FOUNDATION INSERT

• Mounting Bolt Hole cutout (from sketch on aluminum bar) (originally 5mm): M4_mounting_bolt_clearance_hole_diameter (4mm)

TOP SHEETH (COVER) -- finished top mounting hole and nut updates and fillet on d-ring cutout in V115

• Mounting Bolt Head diameter (originally 9.9): M4_mounting_bolt_head_diameter + gap * 3 (8.6mm)
• Mounting Nut half width (originally 4mm): M4_mounting_nut_width / 2 (3.5mm)
• extrusion depth for Mounting Nut (originally 3.2): M4_mounting_nut_height + gap (3.4)
• D-Ring Fillet: 2mm
• extra height on extrusion (originally 1): 1mm

[EfficiencyJunky]

All M4 Updates complete in V117