Arsenal/Compat RHS - Improve support for RHS attachments

[LinkIsGrim]

When merged this pull request will:

• Add event ace_arsenal_weaponItemChanged: params _weapon, _item, _itemIndex. _itemIndex is relative to ace_arsenal_currentItems attachment array. Documented. Fires on weapon attachment/magazine change.
• Use above event to call RHS's function for optic/attachment switching.
• Add baseWeapon property to RHS rail attachments.
• Add handling in ace_arsenal_fnc_scanConfig for RHS scripted optics. Overrides baseWeapon cache.

Partial address of #9384.

Prevents this:

And this:

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Done