Consider allowing auto advance even when not focused?

> Secondly, I would also love for the auto advance feature to continue to advance when the Anki window is not in focus. As it is now, it automatically disables when a different window is in focus, which is unfortunate.

Originally reported on https://forums.ankiweb.net/t/auto-advance-features/64549

The current behaviour was chosen to minimize the chances of the user accidentally answering all their cards when they get distracted and switch away from the app, but as they require a menu/shortcut key to start auto advance, maybe it's reasonable to assume they'll know how to stop it too.