Code style improvements in JavaScript (#13159)

* JS-linter: fix trailing comma's

* Configure eslinter to ignore this onchange error.

app/javascript/mastodon/store/configureStore.js

@@ -10,6 +10,6 @@ export default function configureStore() {
     thunk,
     loadingBarMiddleware({ promiseTypeSuffixes: ['REQUEST', 'SUCCESS', 'FAIL'] }),
     errorsMiddleware(),
-    soundsMiddleware()
+    soundsMiddleware(),
   ), window.__REDUX_DEVTOOLS_EXTENSION__ ? window.__REDUX_DEVTOOLS_EXTENSION__() : f => f));
 };