`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`.
{
    std::lock_guard lock(shared->embedded_dictionaries_mutex);
    if (!shared->embedded_dictionaries)
    {
        auto geo_dictionaries_loader = std::make_unique<GeoDictionariesLoader>();
        shared->embedded_dictionaries = std::make_unique<EmbeddedDictionaries>(
            std::move(geo_dictionaries_loader),
            getGlobalContext(),
            throw_on_error);
    }
    return *shared->embedded_dictionaries;
}
void Context::tryCreateEmbeddedDictionaries(const Poco::Util::AbstractConfiguration & config) const