Add "Always allow product use in construction" option to storages

This would allow the keep full slider on storages to be ignored by trucks when sourcing items for construction purposes. This would be very useful for things like rubber, electronics, etc that are used very infrequently or in small amounts in construction and don't really justify a full train car for delivery.
It would allow you to set up small storages in your construction zones that would be stocked by trucks without the need to keep flipping the fill slider on and off in order to get the products where you need them