aco: rework the way various compilation/validation errors are reported

The upcoming change will allow to report all ACO errors (or warnings)
directly to the app via VK_EXT_debug_report. This is similar to what
we already do for reporting various SPIRV->NIR errors.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6318>