Add support for V3D_DEBUG=clif. Useful to compare clif_dumps from vulkan small-programs and the equivalent opengl ones. As we are here we expand clif_dump_packet wrapper to use v3d42_clif_dump_packet if needed, as the vulkan driver would use that packet version. Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6766>