4c60a11d8f had to be reverted, because it
broke restoring the state of hidden, floating dock widgets.
Extend tst_QDockWdget::hideAndShow() to test this functionality.
Blacklist test function on Apple, because Apple machines on CI show
dock widgets with the main window.
Task-number: QTBUG-120191
Pick-to: 6.7
Change-Id: Ibc6121a99f15f33d62ca0a9376dbe9fafbe20290
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
3195e34742