feat: Cart Customer link + create cart with customer (#6426)

packages/link-modules/src/definitions/cart-customer.ts

@@ -0,0 +1,28 @@
+import { Modules } from "@medusajs/modules-sdk"
+import { ModuleJoinerConfig } from "@medusajs/types"
+
+export const CartCustomer: ModuleJoinerConfig = {
+  isLink: true,
+  isReadOnlyLink: true,
+  extends: [
+    {
+      serviceName: Modules.CART,
+      relationship: {
+        serviceName: Modules.CUSTOMER,
+        primaryKey: "id",
+        foreignKey: "customer_id",
+        alias: "customer",
+      },
+    },
+    {
+      serviceName: Modules.CUSTOMER,
+      relationship: {
+        serviceName: Modules.CART,
+        primaryKey: "customer_id",
+        foreignKey: "id",
+        alias: "carts",
+        isList: true,
+      },
+    },
+  ],
+}

packages/link-modules/src/definitions/index.ts

@@ -1,3 +1,4 @@
+export * from "./cart-customer"
 export * from "./cart-region"
 export * from "./cart-sales-channel"
 export * from "./inventory-level-stock-location"