feat(medusa): Add /admin/products/:id/variants end point (#1471)

* feat(medusa): Add /admin/products/:id/variants end point

* test(medusa): Fix get-variants test casees

* feat(medusa): Include the config to the ProdutService#retrieveVariants as a method parameter

* feat(medusa): Improve get-variants endpoint

* feat(medusa): Improve get-variants endpoint

* test(medusa): Fix unit tests

* test(medusa): Fix unit tests

* feat(medusa): Improve typings

* feat(medusa): Update according to feedback

* feat(medusa): Update according to feedback

* test(medusa): Fix list-variants tests

* feat(medusa): Getting the variants from the product end point should use the productVariantService

* fix(medusa): list-variants expand possibly undefined

* Fix(medusa): List-variants endpoint

* fix(medusa): Tests suite for list-variant

* test(integration-tests): Fix yarn lock

* test(integration-tests): Fix yarn lock

packages/medusa/src/utils/get-query-config.ts

@@ -30,14 +30,14 @@ export function getRetrieveConfig<TModel extends BaseEntity>(
 ): FindConfig<TModel> {
   let includeFields: (keyof TModel)[] = []
   if (typeof fields !== "undefined") {
-    const fieldSet = new Set(fields)
-    fieldSet.add("id")
-    includeFields = Array.from(fieldSet) as (keyof TModel)[]
+    includeFields = Array
+      .from(new Set([...fields, "id"]))
+      .map(field => (typeof field === "string") ? field.trim() : field) as (keyof TModel)[]
   }
 
   let expandFields: string[] = []
   if (typeof expand !== "undefined") {
-    expandFields = expand
+    expandFields = expand.map(expandRelation => expandRelation.trim())
   }
 
   return {