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`
#include <Parsers/IAST.h>
#include <Parsers/ASTSystemQuery.h>
#include <Common/quoteString.h>
#include <IO/Operators.h>
namespace DB
{
namespace ErrorCodes
{
    extern const int LOGICAL_ERROR;
}
const char * ASTSystemQuery::typeToString(Type type)
{
    switch (type)
    {
        case Type::SHUTDOWN:
            return "SHUTDOWN";
        case Type::KILL:
            return "KILL";
        case Type::DROP_DNS_CACHE:
            return "DROP DNS CACHE";
        case Type::DROP_MARK_CACHE:
            return "DROP MARK CACHE";
        case Type::DROP_UNCOMPRESSED_CACHE:
            return "DROP UNCOMPRESSED CACHE";
#if USE_EMBEDDED_COMPILER
        case Type::DROP_COMPILED_EXPRESSION_CACHE:
            return "DROP COMPILED EXPRESSION CACHE";