Lock
`Lock` must return `apistatus.IrregularObjectLock` error instead of `apistatus.ObjectLocked` one. Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
Implement `StorageEngine.Lock` method which works similar to `Inhume` but calls `Lock` on the processing shards. Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>