feat: Custom line items (#10408)

* feat: Custom line items

* fix tests

* fix migration

* Allow custom items in update line item workflow

* throw if line item doesn't have a price

* minor things

* wip

* fix flows

* fix test

* add default

* add to type

integration-tests/http/__tests__/order/admin/order.spec.ts

@@ -1,5 +1,5 @@
-import { ModuleRegistrationName } from "@medusajs/utils"
 import { medusaIntegrationTestRunner } from "@medusajs/test-utils"
+import { ModuleRegistrationName } from "@medusajs/utils"
 import {
   adminHeaders,
   createAdminUser,