This reverts most of commit f420c143e0
again because it turns out GPUs like combined images and samplers.
But: The one thing we don't revert is allowing the C code to select any
combination of sampler and image:
gsk_vulkan_render_get_image_descriptor() now takes a 2nd argument
specifying the sampler.
This allows the same flexibility as before, we just combine things
early.
This change was inspired by
https://developer.nvidia.com/blog/vulkan-dos-donts/
The idea here is that we can do more complex combinations and use that
to support texture-scale nodes or use fancy texture formats (suc as
YUV).
I'm not sure this is actually necessary, but for now it gives more
flexibility.
Instead of having a descriptor set per operation, we just have one
descriptor set and bind all our images into it.
Then the shaders get to use an index into the large texture array
instead.
Getting this to work - because it's a Vulkan extension that needs to be
manually enabled, even though it's officially part of Vulkan 1.2 - is
insane.
Move the resources of each renderer to its subdirectory.
We've previously done that for the ngl renderer, but it
is better to be consistent and do it for all the renderers.
