Accessory Refactor - True Helmet Accessories & Corporate Protection Masks

[1Sparky1]

Redesigns the entire accessory system to work based on slots (uniform, suit, head or helmet) and type (generic, utility & armour plates).

Added corporate protection masks, which can be selected from the loadout by security, and can be attached to helmets.

~~Also re-organised all accessories to be contained sprites, because I was there.~~ This was causing issues with the icon diffs being too large I think. I'll do this some other time.