Bose A20 Control Module Mount - Clean Geometry

I wanted to make some modifications to [victor_1955](https://www.thingiverse.com/victor_1955)'s [Bose A20 Control Module Mount](https://www.thingiverse.com/thing:6432684) for a specific application, but ran into some issues with the geometry. Fusion360 tends to create meshes with quite a few issues, and this seems to be the case for this model. I set about trying to correct them, and ended up with nearly a complete redraw. The only thing that was kept from the original is one half of the interior top-down profile.

The vast majority of changes are not easily discernable to the naked eye, but include:
- Longitudinally mirror symetrical
- Semi-consistent thickness based on top radius (0.0625")
- Interior-exterior edge symetry
- Added interior radius to bottom (0.125")
- Slightly increases strength
- Added exterior radius to bottom (0.125")
- Eliminate sharp edges
- Gussets redrawn from single radius
- Smooth transition to interior profile (no microscopic surfaces)
- Eliminated all