feat: define link util (#7931)

* feat: define link util

* handle pluralized fieldAlias for isList

* serviceName ar reference

* finalize

* todo

* WIP

* finalize

* fix tests

* update typings

* fix Module

* linkable

* update errors

packages/modules/region/src/models/country.ts

@@ -1,7 +1,7 @@
 import { model } from "@medusajs/utils"
 import Region from "./region"
 
-const Country = model
+export default model
   .define(
     { name: "Country", tableName: "region_country" },
     {
@@ -24,5 +24,3 @@ const Country = model
       unique: true,
     },
   ])
-
-export default Country

packages/modules/region/src/models/index.ts

@@ -1,3 +1,2 @@
-export { default as RegionCountry } from "./country"
+export { default as Country } from "./country"
 export { default as Region } from "./region"
-

packages/modules/region/src/models/region.ts

@@ -1,7 +1,7 @@
 import { model } from "@medusajs/utils"
 import RegionCountry from "./country"
 
-const Region = model.define("region", {
+export default model.define("region", {
   id: model.id({ prefix: "reg" }).primaryKey(),
   name: model.text().searchable(),
   currency_code: model.text().searchable(),
@@ -9,5 +9,3 @@ const Region = model.define("region", {
   countries: model.hasMany(() => RegionCountry),
   metadata: model.json().nullable(),
 })
-
-export default Region