UI 자동화를 위해 바인딩 기능 구현

- 유니티 에셋 인증 오류로 meta 재생성

Packages/com.unity.inputsystem/InputSystem/Utilities/Observables/Observer.cs

@@ -0,0 +1,31 @@
+using System;
+
+namespace UnityEngine.InputSystem.Utilities
+{
+    internal class Observer<TValue> : IObserver<TValue>
+    {
+        private Action<TValue> m_OnNext;
+        private Action m_OnCompleted;
+
+        public Observer(Action<TValue> onNext, Action onCompleted = null)
+        {
+            m_OnNext = onNext;
+            m_OnCompleted = onCompleted;
+        }
+
+        public void OnCompleted()
+        {
+            m_OnCompleted?.Invoke();
+        }
+
+        public void OnError(Exception error)
+        {
+            Debug.LogException(error);
+        }
+
+        public void OnNext(TValue evt)
+        {
+            m_OnNext?.Invoke(evt);
+        }
+    }
+}