This encapsulates all the little bits needed to turn a shader module
into some mostly reasonable NIR. It handles inlining functions,
lowering variable initializers, handling per-member structs and other
trickiness that is needed for consuming the output of spirv_to_nir.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15305>