[Order Refactor] [Delivery] Implement delivery mock APIs for checkout/order processing

[mochacr0]

During the checkout/order process, there is a need to choose shipment providers and calculate shipment fees (including taxes and total cost). Since the delivery services have not yet been designed and implemented, we need to create mock APIs to allow the checkout/order development to proceed without blockers.

Proposed Mock APIs:

• Get all available shipment providers API [OrderRefactor][Order][Checkout] Fulfill Checkout information #1110

• Calculate shipment fees API [OrderRefactor][Order][Checkout] Fulfill Checkout information #1110