[wip] add groups/categories to all "list" settings

[chri-k]

breaks addons, currently breaks configs

Type of change

• [ ] Bug fix
• [x] New feature

Description

adds user-definable and pre-defined groups of items to "list" settings (which are actually set settings). groups are saved per setting type, and will update the effective value of all settings using them whenever modified.

State

this is not fully implemented. some features are broken. changes made for the purpose of debugging are included. this will break configs. (and config save/load might be broken anyway).

code is in volatile debugging form, and needs to be condensed and cleaned.

Related issues

not enumerated. likely conflicts with half of all other PRs

How Has This Been Tested?

testing is incomplete; see discord; see added TODO / XXX comments

Checklist:

conditions not met