Create the ability to set a static quantity on hand or quantity available for an item or a group of items

This functionality would allow dealers who have KIT skus that are created from other in-stock items (such as building kits, deck kits, fencing kits, Milwaukee Packout Kits, etc) the ability show a Quantity Available and the item would then be able to be added to cart. Another use case would be for bulk items that the dealer does not "Keep Stock" keep track of QOH in ERP such as bulk screws, cut plywood & sheetrock (it's technically always available, since it's cut from an in-stock 4'x8' piece) bulk hardware that is sold by the each under a generic sku but the item is also sold by the box, but since there is no QOH in the ERP the item can't be displayed or added to cart.