Enforce trailing comma in JS on multiline (#30002)

To keep blame info accurate and to avoid [changes like
this](https://github.com/go-gitea/gitea/pull/29977/files#diff-c3422631a14edbe1e508c4b22f0c718db318be08a6e889427802f9b6165d88d6R359),
it's good to always have a trailing comma, so let's enforce it in JS.

This rule is completely automatically fixable with `make lint-js-fix`
and that's what I did here.

webpack.config.js

@@ -178,7 +178,7 @@ export default {
                 ],
               },
             },
-          }
+          },
         ],
       },
       {
@@ -191,14 +191,14 @@ export default {
         type: 'asset/resource',
         generator: {
           filename: 'fonts/[name].[contenthash:8][ext]',
-        }
+        },
       },
       {
         test: /\.png$/i,
         type: 'asset/resource',
         generator: {
           filename: 'img/webpack/[name].[contenthash:8][ext]',
-        }
+        },
       },
     ],
   },