refactor: Use kebab-case for app auth client serializer filename

packages/backend/src/serializers/app-auth-client.js

@@ -0,0 +1,10 @@
+const appAuthClientSerializer = (appAuthClient) => {
+  return {
+    id: appAuthClient.id,
+    appConfigId: appAuthClient.appConfigId,
+    name: appAuthClient.name,
+    active: appAuthClient.active,
+  };
+};
+
+export default appAuthClientSerializer;