feat(link-modules,modules-sdk, utils, types, products) - Remote Link and Link modules (#4695)

What:
- Definition of all Modules links
- `link-modules` package to manage the creation of all pre-defined link or custom ones

```typescript
import { initialize as iniInventory } from "@medusajs/inventory";
import { initialize as iniProduct } from "@medusajs/product";

import {
  initialize as iniLinks,
  runMigrations as migrateLinks
} from "@medusajs/link-modules";

await Promise.all([iniInventory(), iniProduct()]);


await migrateLinks(); // create tables based on previous loaded modules

await iniLinks(); // load link based on previous loaded modules

await iniLinks(undefined, [
  {
    serviceName: "product_custom_translation_service_link",
    isLink: true,
    databaseConfig: {
      tableName: "product_transalations",
    },
    alias: [
      {
        name: "translations",
      },
    ],
    primaryKeys: ["id", "product_id", "translation_id"],
    relationships: [
      {
        serviceName: Modules.PRODUCT,
        primaryKey: "id",
        foreignKey: "product_id",
        alias: "product",
      },
      {
        serviceName: "custom_translation_service",
        primaryKey: "id",
        foreignKey: "translation_id",
        alias: "transalation",
        deleteCascade: true,
      },
    ],
    extends: [
      {
        serviceName: Modules.PRODUCT,
        relationship: {
          serviceName: "product_custom_translation_service_link",
          primaryKey: "product_id",
          foreignKey: "id",
          alias: "translations",
          isList: true,
        },
      },
      {
        serviceName: "custom_translation_service",
        relationship: {
          serviceName: "product_custom_translation_service_link",
          primaryKey: "product_id",
          foreignKey: "id",
          alias: "product_link",
        },
      },
    ],
  },
]); // custom links
```

Remote Link

```typescript
import { RemoteLink, Modules } from "@medusajs/modules-sdk";

// [...] initialize modules and links

const remoteLink = new RemoteLink();

// upsert the relationship
await remoteLink.create({ // one (object) or many (array)
  [Modules.PRODUCT]: {
    variant_id: "var_abc",
  },
  [Modules.INVENTORY]: {
    inventory_item_id: "iitem_abc",
  },
  data: { // optional additional fields
    required_quantity: 5
  }
});

// dismiss (doesn't cascade)
await remoteLink.dismiss({ // one (object) or many (array)
  [Modules.PRODUCT]: {
    variant_id: "var_abc",
  },
  [Modules.INVENTORY]: {
    inventory_item_id: "iitem_abc",
  },
});

// delete
await remoteLink.delete({
  // every key is a module
  [Modules.PRODUCT]: {
    // every key is a linkable field
    variant_id: "var_abc", // single or multiple values
  },
});

// restore
await remoteLink.restore({
  // every key is a module
  [Modules.PRODUCT]: {
    // every key is a linkable field
    variant_id: "var_abc", // single or multiple values
  },
});

```

Co-authored-by: Riqwan Thamir <5105988+riqwan@users.noreply.github.com>

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

@@ -0,0 +1,2 @@
+export * from "./inventory-level-stock-location"
+export * from "./product-variant-inventory-item"

packages/link-modules/src/definitions/inventory-level-stock-location.ts

@@ -0,0 +1,19 @@
+import { ModuleJoinerConfig } from "@medusajs/types"
+import { Modules } from "@medusajs/modules-sdk"
+
+export const InventoryLevelStockLocation: ModuleJoinerConfig = {
+  isLink: true,
+  isReadOnlyLink: true,
+  extends: [
+    {
+      serviceName: Modules.INVENTORY,
+      relationship: {
+        serviceName: Modules.STOCK_LOCATION,
+        primaryKey: "id",
+        foreignKey: "location_id",
+        alias: "stock_locations",
+        isList: true,
+      },
+    },
+  ],
+}

packages/link-modules/src/definitions/product-variant-inventory-item.ts

@@ -0,0 +1,66 @@
+import { Modules } from "@medusajs/modules-sdk"
+import { ModuleJoinerConfig } from "@medusajs/types"
+import { LINKS } from "../links"
+
+export const ProductVariantInventoryItem: ModuleJoinerConfig = {
+  serviceName: LINKS.ProductVariantInventoryItem,
+  isLink: true,
+  databaseConfig: {
+    tableName: "product_variant_inventory_item",
+    idPrefix: "pvitem",
+    extraFields: {
+      required_quantity: {
+        type: "integer",
+        defaultValue: "1",
+      },
+    },
+  },
+  alias: [
+    {
+      name: "product_variant_inventory_item",
+    },
+    {
+      name: "product_variant_inventory_items",
+    },
+  ],
+  primaryKeys: ["id", "variant_id", "inventory_item_id"],
+  relationships: [
+    {
+      serviceName: Modules.PRODUCT,
+      primaryKey: "id",
+      foreignKey: "variant_id",
+      alias: "variant",
+      args: {
+        methodSuffix: "Variants",
+      },
+    },
+    {
+      serviceName: Modules.INVENTORY,
+      primaryKey: "id",
+      foreignKey: "inventory_item_id",
+      alias: "inventory",
+      deleteCascade: true,
+    },
+  ],
+  extends: [
+    {
+      serviceName: Modules.PRODUCT,
+      relationship: {
+        serviceName: LINKS.ProductVariantInventoryItem,
+        primaryKey: "variant_id",
+        foreignKey: "id",
+        alias: "inventory_items",
+        isList: true,
+      },
+    },
+    {
+      serviceName: Modules.INVENTORY,
+      relationship: {
+        serviceName: LINKS.ProductVariantInventoryItem,
+        primaryKey: "inventory_item_id",
+        foreignKey: "id",
+        alias: "variant_link",
+      },
+    },
+  ],
+}