Really copying Jason's pass.
Changes:
- Instead of all the intel lowering introduce rt_{execute_callable,trace_ray,resume}
- Add the ability to use scratch intrinsics directly.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10339>
