drm/xe: Add xe_exec_queue_last_fence_test_dep

Helpful to determine if a bind can immediately use CPU or needs to be
deferred a drm scheduler job.

v7:
 - Better wording in kernel doc (Matthew Auld)

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240704041652.272920-4-matthew.brost@intel.com