Maintain the implementation with ApplicationItem and the breadcrumb toolbar,
but make the dialog look like a normal config dialog again,
consistent with apps config dialogs

The sidebar is not in the pagerow, as is not part of the page navigation
(and such never appear on the breadcrumb)

Separator lines are present only iff the content don't fit and there is a scrollbar to make
scrollbar look right and items to be clipped with a line instead of in the nothing