Since depth/stencil images can't be linear, I needed buffer/image copies
to test those, and conversely to test buffer/image copies I needed image
clears.
A pretty big chunk of work, and it led to a discovery of a SwiftShader
bug, which I will work around next. First Vulkan driver workaround, so
the whole scaffolding needs to get added as well.
After I implemented the render pass wrapper, seeing how the
RenderPassCreateInfo structure and its dependencies were HUGE compared
to the actual tiny and lean RenderPass, I felt uneasy dragging their
definition along to every place where a RenderPass gets used. It's not
as bad with the others, but as new extensions are implemented I expect
that to get the same.
This change makes it easier for me to accept that Image.h / Buffer.h
depends on Memory.h. There isn't a real measurable difference when
building Magnum itself (50 ms out of 7 seconds for the Vk library
alone), but that's because most of the code (and tests) needs the
CreateInfo structures anyway.
Similarly to Corrade Assert.h, so it's possible to include this header
without having to worry about irrelevant overhead when asserts are
disabled.
Also test it properly, as it should have been from the start.