Instead of checking for MESA_SHADER_COMPUTE (and KERNEL). Where
appropriate, also use gl_shader_stage_is_compute().
This allows most of the workgroup-related lowering to be applied to
Task and Mesh shaders. These will be added later and "inherit" from
cs_prog_data structure.
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13629>
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