[S] Fixes an exploit with mecha ranges (ParadiseSS13#31508)

* mecha melee attacks respect adjacency

* use chassis instead of loc

Author: BiancaWilkson

code/game/mecha/equipment/mecha_equipment.dm

@@ -64,6 +64,8 @@
 		return FALSE
 	if(!chassis)
 		return FALSE
+	if(!is_ranged() && !chassis.Adjacent(target))
+		return FALSE
 	if(!equip_ready)
 		return FALSE
 	if(energy_drain && !chassis.has_charge(energy_drain))