turnip: Add limited support for storage images.

turnip: Add limited support for storage images.

So far this doesn't handle the texture state-based storage image access
loads, and doesn't support descriptor arrays (same as SSBOs).  The texture
side is more tricky, since we have another remapping table to work around.

This is enough to get some of dEQP-VK.image.atomic_operations.* working.

Reviewed-by: Jonathan Marek <jonathan@marek.ca>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3433>