zdtm: Check that 'tcp-close' option closes sockets

There are 2 test cases:
1. Connected socket should be restored in the closed state
2. Listening socket state should not change after restore

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Eugene Batalov <eabatalov89@gmail.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>