Adds a lower body inventory slot. [IDB IGNORE]

[MistakeNot4892]

Description of changes

Adds a pants slot.

Why and what will this PR improve

Allows for some more interesting layering interactions, also supports clothing schemes that aren't entirely based on jumpsuits a bit better.

TODO

• [X] Add slot
• [X] Test slot
• [ ] Add shirt tucking
• [ ] Test layering

Authorship

Myself.

Changelog

:cl: tweak: The uniform slot has been split into upper and lower body slots. Various items are now either pants items, or split into a pants and a shirt item. Jumpsuits, for example, now count as pants. This is a broad change so please report issues to the tracker. /:cl:

[MistakeNot4892]

Need to rebase this but when I do it will depend on #3798.

[MistakeNot4892]

With the reworking of accessories and clothing stacking, I think this slot is probably unnecessary now. Going to close it for the time being unless a pressing need for it comes up again in the future.