Fix(medusa): Missing location id on fulfillments (#3462)

**What**
- include location id when creating a fulfillment
- Allow location updates to reservations without passing along quantity

**Why**
- location_id on fulfillment was null after creation

Fixes CORE-1242, CORE-1243

packages/admin-ui/ui/src/domain/orders/details/create-fulfillment/index.tsx

@@ -170,6 +170,10 @@ const CreateFulfillmentModal: React.FC<CreateFulfillmentModalProps> = ({
           no_notification: noNotis,
         } as AdminPostOrdersOrderFulfillmentsReq
 
+        if (isLocationFulfillmentEnabled) {
+          requestObj.location_id = locationSelectValue.value
+        }
+
         requestObj.items = Object.entries(quantities)
           .filter(([, value]) => !!value)
           .map(([key, value]) => ({

packages/inventory/src/services/reservation-item.ts

@@ -166,7 +166,6 @@ export default class ReservationItemService extends TransactionBaseService {
 
       const shouldUpdateLocation =
         isDefined(data.location_id) &&
-        isDefined(data.quantity) &&
         data.location_id !== item.location_id
 
       const ops: Promise<unknown>[] = []
@@ -185,7 +184,7 @@ export default class ReservationItemService extends TransactionBaseService {
             .adjustReservedQuantity(
               item.inventory_item_id,
               data.location_id!,
-              data.quantity!
+              data.quantity || item.quantity!
             )
         )
       } else if (shouldUpdateQuantity) {

packages/medusa/src/api/routes/admin/orders/create-fulfillment.ts

@@ -121,6 +121,7 @@ export default async (req, res) => {
     await orderServiceTx.createFulfillment(id, validatedBody.items, {
       metadata: validatedBody.metadata,
       no_notification: validatedBody.no_notification,
+      location_id: validatedBody.location_id,
     })
 
     if (validatedBody.location_id) {