feat(cart): POST /store/carts (#6273)

Depends on #6262

packages/cart/integration-tests/__tests__/services/cart-module/index.spec.ts

@@ -5,7 +5,7 @@ import { initModules } from "medusa-test-utils"
 import { MikroOrmWrapper } from "../../../utils"
 import { getInitModuleConfig } from "../../../utils/get-init-module-config"
 
-jest.setTimeout(30000)
+jest.setTimeout(50000)
 
 describe("Cart Module Service", () => {
   let service: ICartModuleService