zink: track min_samples state for per sample shading
Vulkan pipeline state sampleShadingEnable and minSampleShading are directly related to GL_SAMPLE_SHADING_ARB. Track min_smaples provided by st and include it in pipeline state. This was seen as failures in cts cases where per sample shading along with sample interpolation qualifiers are tested: dEQP-GL45-ES31.functional.shaders.multisample_interpolation.sample_qualifier.*
Cc: mesa-stable