feat(medusa): allow category list api to be filtered by handle (#3825)

what:

- Introduce a filter to the list endpoint to query by handle

why:

- Storefronts mostly interact through handles and not IDs for readability and seo purposes - Take an example of a url `site.com/category/mens-wear`

RESOLVES CORE-1325

integration-tests/api/__tests__/admin/product-category.ts

@@ -305,6 +305,19 @@ describe("/admin/product-categories", () => {
       expect(response.data.product_categories[0].id).toEqual(productCategory.id)
     })
 
+    it("filters based on handle attribute of the data model", async () => {
+      const api = useApi()
+
+      const response = await api.get(
+        `/admin/product-categories?handle=${productCategory.handle}`,
+        adminHeaders,
+      )
+
+      expect(response.status).toEqual(200)
+      expect(response.data.count).toEqual(1)
+      expect(response.data.product_categories[0].id).toEqual(productCategory.id)
+    })
+
     it("filters based on free text on name and handle columns", async () => {
       const api = useApi()
 

integration-tests/api/__tests__/store/product-category.ts

@@ -300,6 +300,18 @@ describe("/store/product-categories", () => {
       expect(response.data.product_categories[0].id).toEqual(productCategoryParent.id)
     })
 
+    it("filters based on handle attribute of the data model", async () => {
+      const api = useApi()
+
+      const response = await api.get(
+        `/store/product-categories?handle=${productCategory.handle}`,
+      )
+
+      expect(response.status).toEqual(200)
+      expect(response.data.count).toEqual(1)
+      expect(response.data.product_categories[0].id).toEqual(productCategory.id)
+    })
+
     it("filters based on parent category", async () => {
       const api = useApi()