Node's maintenance state can be set only if the network allows it.
Make `neofs-cli control set-status` to read current network settings and
check is maintenance state is allowed. Fail the execution if the mode is
not allowed.
Signed-off-by: Leonard Lyubich <ctulhurider@gmail.com>
If the key can't be fetched, an error is always returned, so it makes
sense to fail the whole command inside of a `key.Get*()`.
Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
