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`
if (!query.storage_policy.empty() && !query.volume.empty())
        volume_ptr = context.getStoragePolicy(query.storage_policy)->getVolumeByName(query.volume);
    switch (query.type)
    {
        case Type::SHUTDOWN:
            context.checkAccess(AccessType::SYSTEM_SHUTDOWN);
            if (kill(0, SIGTERM))
                throwFromErrno("System call kill(0, SIGTERM) failed", ErrorCodes::CANNOT_KILL);
            break;
        case Type::KILL:
            context.checkAccess(AccessType::SYSTEM_SHUTDOWN);
            if (kill(0, SIGKILL))
                throwFromErrno("System call kill(0, SIGKILL) failed", ErrorCodes::CANNOT_KILL);
            break;
        case Type::DROP_DNS_CACHE:
            context.checkAccess(AccessType::SYSTEM_DROP_DNS_CACHE);
            DNSResolver::instance().dropCache();
            
            system_context.reloadClusterConfig();
            break;
        case Type::DROP_MARK_CACHE:
            context.checkAccess(AccessType::SYSTEM_DROP_MARK_CACHE);
            system_context.dropMarkCache();
            break;
        case Type::DROP_UNCOMPRESSED_CACHE:
            context.checkAccess(AccessType::SYSTEM_DROP_UNCOMPRESSED_CACHE);
            system_context.dropUncompressedCache();
            break;
#if USE_EMBEDDED_COMPILER
        case Type::DROP_COMPILED_EXPRESSION_CACHE: