Add callback for attack target

I'm creating an event where infection is implemented in PLAYER_KILL mode, not by hit, because currently LuaAPI doesn't expose a reliable attack/hit callback to trigger character infection upon receiving an attack.

Therefore, I'm requesting a callback that captures the moment of the attack on the target (oPlayer), as currently we only have the death callback.

The idea would be a callback that intercepts the target's first hits.

onPlayerAttackHit(oPlayer, target)