Add a command that will freeze clickhouse-server process with STOP signal and wakeup it after specified amount of time.
This is needed for testing (fault injection).

Wakeup can be done with `ShellCommand` running `sleep N && kill -CONT pid`
#endif
        case Type::STOP_LISTEN_QUERIES:
            return "STOP LISTEN QUERIES";
        case Type::START_LISTEN_QUERIES:
            return "START LISTEN QUERIES";
        case Type::RESTART_REPLICAS:
            return "RESTART REPLICAS";
        case Type::RESTART_REPLICA:
            return "RESTART REPLICA";
        case Type::DROP_REPLICA:
            return "DROP REPLICA";
        case Type::SYNC_REPLICA:
            return "SYNC REPLICA";
        case Type::FLUSH_DISTRIBUTED:
            return "FLUSH DISTRIBUTED";
        case Type::RELOAD_DICTIONARY:
            return "RELOAD DICTIONARY";
        case Type::RELOAD_DICTIONARIES:
            return "RELOAD DICTIONARIES";
        case Type::RELOAD_EMBEDDED_DICTIONARIES:
            return "RELOAD EMBEDDED DICTIONARIES";
        case Type::RELOAD_CONFIG:
            return "RELOAD CONFIG";
        case Type::RELOAD_SYMBOLS:
            return "RELOAD SYMBOLS";
        case Type::STOP_MERGES:
            return "STOP MERGES";
        case Type::START_MERGES:
            return "START MERGES";
        case Type::STOP_TTL_MERGES: