After fixing the data type for D24S8, we can now implement attaching
depth and stencil (with the same texture).
For Metal we need to set a stencil flag correctly.
This allows using D24S8 in the manual test, which is likely the format
that is going to be commonly used when setting up multiview with
Qt Quick.
Fixes: QTBUG-114904
Change-Id: Ife425c6cb3e09bfe40092c841b78f7a93bb6a4cd
Reviewed-by: Andy Nichols <andy.nichols@qt.io>
277de5ca4b