`DataTypeFactory::get` locks a mutex inside shared a context, there was a case when many threads were locked inside it

https://pastila.nl/?0043b3e6/c557368f4cf0eb87a3c6f2cc162bc693

It is not clear which thread locked the mutex for a long time. However, it may be possible to lock less inside `DataTypeFactory::get`.
{
    auto lock = getLock();
    return shared->tmp_volume;
}
void Context::setPath(const String & path)
{
    auto lock = getLock();
    shared->path = path;
    if (shared->tmp_path.empty() && !shared->tmp_volume)
        shared->tmp_path = shared->path + "tmp/";
    if (shared->flags_path.empty())
        shared->flags_path = shared->path + "flags/";
    if (shared->user_files_path.empty())
        shared->user_files_path = shared->path + "user_files/";
    if (shared->dictionaries_lib_path.empty())
        shared->dictionaries_lib_path = shared->path + "dictionaries_lib/";
    if (shared->user_scripts_path.empty())
        shared->user_scripts_path = shared->path + "user_scripts/";
    if (shared->user_defined_path.empty())
        shared->user_defined_path = shared->path + "user_defined/";
}
VolumePtr Context::setTemporaryStorage(const String & path, const String & policy_name)