Optimize the FN connection logic

[SaintWish]

Currently we create a new thread everytime the game server sends the character data to the FN server, and we do it every few seconds to prevent data loss in case of a game server crash. We're also creating a new connection each time too, so both things could use a pooling system to reuse connections and thread.

We should add another method for sending requests async with curl_multi, these requests would be for sending the character data to via FN server since we don't need a response back.