WebUI: enforce coding style

Actually, not all of them but some that can be enforced by eslint.
The changes are made by eslint with minor manual tweaking.

PR #17046.

src/webui/www/private/scripts/preferences.js

@@ -55,7 +55,7 @@ window.qBittorrent.LocalPreferences = (function() {
                 console.error(err);
             }
         }
-    })
+    });
 
     return exports();
 })();