Write a file `uuid` in server's data directory that contains random UUID, generated at startup if file does not exist.

It will be used for several purposes:
- to anonymously identify server in Sentry (currently Sentry is unusable);
- (possible future usage) to identify server in ensemble.

@tavplubix comments?
{
#if defined(THREAD_SANITIZER) && defined(OS_LINUX)
    
    
    (void)syscall(SYS_exit_group, 0);
    __builtin_unreachable();
#else
    _exit(0);
#endif
}
std::string getUserName(uid_t user_id)
{
    
    auto buffer_size = sysconf(_SC_GETPW_R_SIZE_MAX);
    if (buffer_size <= 0)
        buffer_size = 1024;
    std::string buffer;
    buffer.reserve(buffer_size);
    struct passwd passwd_entry;
    struct passwd * result = nullptr;
    const auto error = getpwuid_r(user_id, &passwd_entry, buffer.data(), buffer_size, &result);
    if (error)
        throwFromErrno("Failed to find user name for " + toString(user_id), ErrorCodes::FAILED_TO_GETPWUID, error);
    else if (result)
        return result->pw_name;
    return toString(user_id);
}
}
Poco::Net::SocketAddress Keeper::socketBindListen(Poco::Net::ServerSocket & socket, const std::string & host, UInt16 port, [[maybe_unused]] bool secure) const