Update Shipping Method of an Order Edit

Add Shipping Method to Order Edit POST

Add a shipping method to an exchange. The shipping method will have a `SHIPPING_ADD` action.

Remove Shipping Method from Order Edit DELETE

Remove a shipping method in the order edit by the ID of the method's `SHIPPING_ADD` action. Every shipping method has an `actions` property, whose value is an array of actions. You can check the action's name using its `action` property, and use the value of the `id` property.