SteamNetworkingIdentity support

[violantor]

Hi, Steam has added the ability to use the SteamNetworkingIdentity argument when generating an AuthTicket, is it possible to add support for this feature in your library?

HAuthTicket GetAuthSessionTicket(void *pTicket, int cbMaxTicket, uint32 *pcbTicket, const SteamNetworkingIdentity *pIdentityRemote);

[neonnd]

It was added because you were able to use other players authentication tickets and impersonate them, the newly added protobuf field is just SteamNetworkingIdentity::ToString