API: return resource ID for auth key creation, folder permissions update and user invite complete endpoints (#27419)

* API: add ID to auth key and folder endpoints

* API: add test for folder permissions update

* API: add created user id for /invite/complete endpoint

pkg/api/folder_permission_test.go

@@ -125,6 +125,10 @@ func TestFolderPermissionApiEndpoint(t *testing.T) {
 			updateFolderPermissionScenario("When calling POST on", "/api/folders/uid/permissions", "/api/folders/:uid/permissions", cmd, func(sc *scenarioContext) {
 				callUpdateFolderPermissions(sc)
 				So(sc.resp.Code, ShouldEqual, 200)
+				respJSON, err := simplejson.NewJson(sc.resp.Body.Bytes())
+				So(err, ShouldBeNil)
+				So(respJSON.Get("id").MustInt(), ShouldEqual, 1)
+				So(respJSON.Get("title").MustString(), ShouldEqual, "Folder")
 			})
 
 			Reset(func() {