s4-torture: Add handlers to ignore incoming oplock/lease break requests

s4-torture: Add handlers to ignore incoming oplock/lease break requests

For use in multichannel oplock break tests. These handers ignore
incoming oplock and lease break requests so that we can test the
oplock/lease break retries on the server.

This is meant for use with samba servers which rely on receiving a reply
from the client before timeout.
Windows servers rely on underlying tcp commands to decide if the oplock
break command was delivered successfully to the client and therefore
cannot be tested with this method.

Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Reviewed-by: Guenther Deschner <gd@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>