mesa: support dummy queries for ARB_pipeline_statistics_query

mesa: support dummy queries for ARB_pipeline_statistics_query

Similar to ARB_occlusion_query / ARB_occlusion_query2, this extension
allows zero bits for the queries, meaning there's no actual hardware
requirements here.

So let's just report zero bits if the driver doesn't support the CAP,
and treat these queries as dummies like we already do for occlusion
queries.

We still don't expose the extension, this is just to make it possible to
allow the core OpenGL functionality without exposing the extension.

Reviewed-by: Soroush Kashani <soroush.kashani@imgtec.com>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19750>