Add BetterBags category function

[guicaulada]

Register a category function on the AdiBags successor addon BetterBags.

The category function will create a custom category for each item set and correctly alocate the items on the right category.

Screenshots:

[Breeni]

How does this compare to how BetterBags handles the built in equipment sets? Does renaming sets, adding/removing items, and such keep the BetterBags categories up to date?

[guicaulada]

Changes to gear sets from BetterBags are only reflected upon a reload or a re-sort of the bag by right clicking the bag icon on the top left.

With the current implementation BtWLoadouts is only adding the items to the custom category upon load, so a reload would be necessary to update the sets.

For default equipment sets I know we can tie into EQUIPMENT_SETS_CHANGED but I'm not sure BtWLoadouts fire any events for equipment sets updates within the addon.

[Breeni]

I'm going to extend the internal event system so things can be triggered from changing the sets. There will still probably be issues with items that are in multiple sets possibly not being updated correctly sometimes. It'd also be nice if BetterBags allowed for categories on specific items instead of item ids but that would probably require a more dramatic change on their end