Arsenal - Native baseWeapon support for CBA items

[LinkIsGrim]

When merged this pull request will:

• Add baseWeapon support to all attachments using CBA systems by default.
• Add functions for getting base optic/attachment of an item.
• Close #9384
• Add support for preset backpacks (used as loaded backpacks for units) to the arsenal. They will be saved, loaded and verified as their player-accessible counterparts.
• Close #8252

TODO:

• [ ] Re-verify if base backpack is part of arsenal in FUNC(verifyLoadout)
• [ ] Handle the equipped backpack being a preset class in FUNC(replaceUniqueItemsLoadout)

Adapted from https://github.com/Theseus-Aegis/Mods/blob/master/addons/armory/functions/fnc_getBaseVariant.sqf

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