refactor redis: do not copy additional_infos of geo points

[mishasychev]

• GeoPoint parsing no longer copies the additional_infos array (now taken by reference) and moves the member string out of the reply.
• ExtractStringElem takes the already-fetched element by reference instead of re-looking it up via at()/GetArray() on every call.
• Replaced std::stod/std::stoi with utils::FromString<> for stricter, exception-consistent numeric parsing of scores and timestamps.