refactor: 💡 remove route-action usage for auth-methods (#2178)

* refactor: 💡 remove route-action usage for auth-methods

✅ Closes: https://hashicorp.atlassian.net/browse/ICU-12603

ui/admin/app/controllers/scopes/scope/auth-methods/auth-method/index.js

@@ -0,0 +1,5 @@
+import Controller, { inject as controller } from '@ember/controller';
+
+export default class ScopesScopeAuthMethodsAuthMethodIndexController extends Controller {
+  @controller('scopes/scope/auth-methods/index') authMethods;
+}