Valve Index Frunk Dual 40mm Fan Exhaust Enclosure

Version 2 notes:
I noticed that the index_hmd_accessory_inclusion_zone.stp CAD files released here
https://github.com/ValveSoftware/IndexHardware/tree/master/Headset is incorrect.

Specifically, it doesn't take into account the front, right, upper sensor on the Valve index headset.

I've adjusted the Frunk Exhaust Enclosure to account for that sensor and scaled it up a tiny bit to fit better.