drm/xe/migrate: Add kunit to test migration functionality for BMG

This part of kunit verifies that
- main data is decompressed and ccs data is clear post bo eviction.
- main data is raw copied and ccs data is clear post bo restore.

v2: Added missing bo_put()/bo_unlock() (Matt Auld)

Signed-off-by: Akshata Jahagirdar <akshata.jahagirdar@intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1d36d4377c566508e42b3fb80d3fe4a588fd00ca.1721250309.git.akshata.jahagirdar@intel.com