fix: allow passing idempotency key to service layer create (#2701)

**What**

Allow DraftOrders to be created with an IdempotencyKey. 

Note this doesn't implement idempotency for the DraftOrder create endpoint but allows the service layer to ingest the key and store it in the database. This is a preliminary step to being able to support an idempotent API request.

packages/medusa/src/services/draft-order.ts

@@ -259,8 +259,13 @@ class DraftOrderService extends TransactionBaseService {
           )
         }
 
-        const { shipping_methods, no_notification_order, items, ...rawCart } =
-          data
+        const {
+          shipping_methods,
+          no_notification_order,
+          items,
+          idempotency_key,
+          ...rawCart
+        } = data
 
         const cartServiceTx =
           this.cartService_.withTransaction(transactionManager)
@@ -285,6 +290,7 @@ class DraftOrderService extends TransactionBaseService {
         const draftOrder = draftOrderRepo.create({
           cart_id: createdCart.id,
           no_notification_order,
+          idempotency_key,
         })
         const result = await draftOrderRepo.save(draftOrder)
 

packages/medusa/src/types/draft-orders.ts

@@ -16,6 +16,7 @@ export type DraftOrderCreateProps = {
   no_notification_order?: boolean
   shipping_methods: ShippingMethod[]
   metadata?: Record<string, unknown>
+  idempotency_key?: string
 }
 
 type ShippingMethod = {