drm/xe: Add struct xe_vma_ops abstraction

Having a structure which encapsulates a list of VMA operations will help
enable 1 job for the entire list.

v2:
 - Rebase

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Oak Zeng <oak.zeng@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240425045513.1913039-5-matthew.brost@intel.com