Add zfs.sync.snapshot_rename
Only the single snapshot rename is provided.
The recursive or more complex rename can be scripted.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Andriy Gapon <avg@FreeBSD.org>
Closes #13802