Sv realip kick

Sets a rule to the server to kick the client if it cannot reach at least this security level.

1 = It will kick any player that doesn't respond with a realip packet (only bans slow senders in the worst case, increase sv_realip_timeout to tweak)

2 = It will kick any player that doesn't respond to A2A_PING with A2A_ACK (currently anything but FTE and mQWCL)

3 = It will kick any player that doesn't respond with a challenge (currently anything but FTE)