when an autohide panel is being configured its visibility
is updated to not make it hide until the panel controller is open
this influences availableScreenrect/availableScreenRegion
and makes widgets to move around when the controller is open.
check the visibility stored in the controller as well in order to
exclude those panels from the available computation
added api is not super beautiful but seems to me the least
invasive as a "realvisibility" "pretendedvisibility"
distinction in panelview would be worse
BUG:372248