feat(medusa): Validate LineItems in SalesChannel (#1871)

* wip: validate line item SC

* fix: repository type, remove relation, use sc id, check if cart has associated sc

* feat: setup tests and seeder, change entity retrieval in cart service method

* feat: remove repo usage and method, use Adrien's method from product service to check sc association, add test cases, add seeder entities, accept flag for validating sc on the endpoint

* feat: add a unit test to ensure validation method is called if flag is passed

* feat: allow `validate_sales_channels` flag in other relevant endpoints

* fix: typo

* fix: flag rename

* fix: correct FF in test suites

* fix: address PR feedback

* fix: change error message

* feat: remove query params, guard with FF, refactor

* feat: guard validation in the service

* refactor: rename validation method

* refactor: reorganise tests

* wip: cleanup test file

* wip: revert cart seeder changes use factories

* fix: remove seeder, update mocks

* fix: method name

* fix: units, validate by default

* git: resolve merge conflicts

* refactor: separate line item sales chanel units

Co-authored-by: fPolic <frane@medusajs.com>

packages/medusa/src/api/routes/admin/draft-orders/create-line-item.ts

@@ -1,4 +1,10 @@
-import { IsInt, IsObject, IsOptional, IsString } from "class-validator"
+import {
+  IsBoolean,
+  IsInt,
+  IsObject,
+  IsOptional,
+  IsString,
+} from "class-validator"
 import { MedusaError } from "medusa-core-utils"
 import { EntityManager } from "typeorm"
 import {
@@ -12,6 +18,7 @@ import {
   LineItemService,
 } from "../../../../services"
 import { validator } from "../../../../utils/validator"
+import { FlagRouter } from "../../../../utils/flag-router"
 /**
  * @oas [post] /draft-orders/{id}/line-items
  * operationId: "PostDraftOrdersDraftOrderLineItems"
@@ -92,7 +99,7 @@ export default async (req, res) => {
 
       await cartService
         .withTransaction(manager)
-        .addLineItem(draftOrder.cart_id, line)
+        .addLineItem(draftOrder.cart_id, line, { validateSalesChannels: false })
     } else {
       // custom line items can be added to a draft order
       await lineItemService.withTransaction(manager).create({