Windows: QSystemTray becomes visible when calling setIcon

When creating a QSystemTrayIcon object it becomes directly visible when calling setIcon() even is setVisible(false) is directly set. This not even unwanted but also a regression to at least Qt 5.9.

This is because sendTrayMessage(NIM_ADD) is called in QWindowsSystemTrayIcon::ensureInstalled() regardless of the visible state.

int main(int argc, char *argv[])
{
   QSystemTrayIcon tray;
   tray.setIcon(QIcon::fromTheme("document-new"));
}