Neo-go does not use smartcontract.Parameter to return values
anymore, so it's convertes partly removed from neofs-node.
Signed-off-by: Alex Vanin <alexey@nspcc.ru>
RPC node closes websocket notification channel if it was terminated
or something wrong happened. Subscriber has to check this condition
and alert about this in upper context by closing it's own channel.
Signed-off-by: Alex Vanin <alexey@nspcc.ru>
