QSystemTrayIcon::isSystemTrayAvailable() opens a new file descriptor on each call which isn't closed

Calling QSystemTrayIcon::isSystemTrayAvailable() generates a new connection in QDBusTrayIcon::isSystemTrayAvailable() with a new unique instance ID. These are never closed, so calling QSystemTrayIcon::isSystemTrayAvailable() frequently leads to a crash when it runs out of file descriptors.

I opened a proposal for a fix here: https://codereview.qt-project.org/c/qt/qtbase/+/354631

It might also be preferred to have a non-static function too that can be called when a QSystemTrayIcon is already created, instead of calling the static function which will create a new QDBusTrayIcon on each call. Since a system tray icon can appear / disappear while the program is running. I can create a proposal to add this if you want, but it needs to have a different name, it could be called just: QSystemTrayIcon::isAvailable()