Validate clients

[lechuga16]

Add client validation to the ratemonitor.

[A1mDev]

For what?

[SirPlease]

From checking ~900 log files, it seems that the user is sometimes no longer in-game when the timer triggers on the player_team timer.
Probably could be using a next frame rather than a timer and do a final check rather than having double checking like in the PR.

[lechuga16]

From checking ~900 log files, it seems that the user is sometimes no longer in-game when the timer triggers on the player_team timer. Probably could be using a next frame rather than a timer and do a final check rather than having double checking like in the PR.

done

[A1mDev]

add a check to the event if (!hEvent.GetBool("disconnect")), this will be enough, I think the rest of the checks are redundant.

[A1mDev]

Some natives and forwards in sourcemod already have checks inside! Example: OnClientSettingsChanged, GetClientOfUserId. The client index must also be correct, otherwise there will be a crash in sourcemod.