spirv: Plumb access qualifiers through from image types

spirv: Plumb access qualifiers through from image types

In SPIR-V, the access qualifiers for an image are provided on the image
type.  Assuming no one swaps the types around on us (I think that should
be illegal), this means we can reliably fetch the access qualifiers from
the type itself.  The ops which don't really have an easy-to-fetch type
are the atomics because they use OpImageTexelPointer.  However, those
are only allowed on read/write images and that's the default.

Reviewed-by: Jesse Natalie <jenatali@microsoft.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6578>