drm/xe/kunit: Add simple tests for new xe_args macros

We want to make sure that helper macros are working as expected.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240502223313.2527-3-michal.wajdeczko@intel.com