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`
#pragma once
#include <Parsers/ASTQueryWithOnCluster.h>
#include <Parsers/IAST.h>
#if !defined(ARCADIA_BUILD)
#    include "config_core.h"
#endif
namespace DB
{
class ASTSystemQuery : public IAST, public ASTQueryWithOnCluster
{
public:
    enum class Type