Add ecs ComponentListener

- Add ecs ComponentListener which listens to Component addition and
  removal
- Add RefCounter class used to keep track of moves and copies

CopiumEngine/src/copium/example/HealthChangeSystem.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include "copium/ecs/System.h"
+#include "copium/example/Components.h"
+#include "copium/event/Input.h"
+
+namespace Copium
+{
+  class HealthChangeSystem : public System<HealthC>
+  {
+
+    void RunEntity(Entity entity, HealthC& health) override
+    {
+      if (Input::IsKeyPressed(CP_KEY_K))
+        health.current++;
+      if (Input::IsKeyPressed(CP_KEY_J))
+        health.current--;
+      health.current = std::clamp(health.current, 0, health.max);
+    }
+  };
+}