Coupon code can be used on multiple carts

[RickAcb]

Currently coupon codes can be used on multiple carts and checked out to make a coupon code used more than the allowed usage.

We found 2 options to solve this:

1. Use the coupon on adding on the cart and remove them from carts after a certain amount
Pro: Carts and checkout will provide correct information on the website
Cons: Coupon codes will say that they are used but are not really used

2. Recheck if the coupon was still able to be used when creating the order from the cart
   Pro: Allows the coupon to be used more then allowed amount in carts but not in order
   Cons: Price can suddenly be changed on ordering if the coupon was used, this can make customer complain

We made a PR to solve it on the first option but it can also be solved on 2nd or other way.

[RickAcb]

I recommend that a solution is found for on the 2nd option by adding an extra check in the DB Transaction for creating the order to make absolutely sure that the coupon would still work.

We might pick this up to create a PR about it later but at this moment we don't have time to create it.