[applets/taskmanager] Hide on mouse leaving even if any window requires attention
When any window needs attention, treat the mouse entering and leaving as acknowledging the urgency status and return to passive status afterward.
On X11, execute the following command in a terminal and switch to another window:
sleep 3; xdotool set_window --urgency 1 $WINDOWID
Also see: https://phabricator.kde.org/D12916