Implement health modification on enemy kill; add HealOnKillModifier and update death behavior

Assets/Scripts/Interfaces/IOnKillEffect.cs

@@ -0,0 +1,9 @@
+using UnityEngine;
+
+namespace Interfaces
+{
+    public interface IOnKillEffect
+    {
+        void OnKill(GameObject killer, GameObject victim);
+    }
+}