ceph: add copy_file_range (remote copy operation) testing

ceph: add copy_file_range (remote copy operation) testing

Test remote copy operation (CEPH_OSD_OP_COPY_FROM) with different
combinations of both object sizes and copy sizes.

Test remote copy operation (CEPH_OSD_OP_COPY_FROM) with several
combinations of both object sizes and copy sizes.  It also uses several
combinations of copy ranges.  For example, copying the 1st object in the
src file into:

  1) the beginning (1st object) of dst file,
  2) the end (last object) of dst file and
  3) the middle of the dst file.

Signed-off-by: Luis Henriques <lhenriques@suse.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>