Player list management / authentication
Handles receiving a new connection from a Steam user. This call will ask the Steam
servers to validate the users identity, app ownership, and VAC status. If the Steam servers
are off-line, then it will validate the cached ticket itself which will validate app ownership
and identity. The AuthBlob here should be acquired on the game client using SteamUser()->InitiateGameConnection()
and must then be sent up to the game server for authentication.
Return Value: returns true if the users ticket passes basic checks. pSteamIDUser will contain the Steam ID of this user. pSteamIDUser must NOT be NULL
If the call succeeds then you should expect a GSClientApprove_t or GSClientDeny_t callback which will tell you whether authentication
for the user has succeeded or failed (the steamid in the callback will match the one returned by this call)