fun Cart.getCartEntriesWithDiscountsToDisplay(order: Order): ArrayList<CartEntry>
Used to get a list of entries that include discounts that can be displayed without changing the actual cart entries list. This keeps things safe for when the order is placed and sent to back end. E.g. The discounts should not be sent up as cart entries.
order - The order associated with this Cart.
Return
A list of cartEntries that also includes the order's discounts that can be displayed as line items.