Use `node is under maintenance` message in `NodeUnderMaintenance.Error`
is `message` field is unset in the status message.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
Define `WrongMagicNumber` type for which encapsulates the work with
incorrect network magic. Provide method to read/write the correct magic
(which is a status detail in NeoFS API V2 protocol).
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
Define base `Status` interface. Provide the functionality to distinguish
success and failure returns. Provide functionality to transport statuses
over NeoFS API V2 protocol. Support success `OK` and failure `INTERNAL`
returns.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
