Add IDLE logout timer to the UMS Webapp#482

Currently, the UMS Web app doesn’t have any way to prevent users from being signed in for days (in our own testing) - One of the latest releases allowed you to remove “Stay logged in for 30 days” (https://kb.igel.com/en/universal-management-suite/current/how-to-configure-options-for-the-login-page-in-the-igel-ums-web-app), however even with this disabled, a highly priviliged admin (or, even worse, the built-in super admin) can sign into the webapp and stay signed in into the browser for hours-days with no way of preventing it.