Calculating the cost of delivery in the order for Opencart 2.1.x / 2.3.x

Calculate the cost of delivery in the order.
- Easy installation
- Quick use
- Accessibility in Opencart 2.1.x / 2.3.x versions

Description:
When editing an order in the admin panel, you can change
shipping cost for recalculation with the selected shipping method. Or
return to the original state with the selected delivery method at the same time
just keeping the order without specifying the cost of recalculation.

PS: Does not change the cost of the established delivery methods