move puzzle implementations out of engine

Assets/Engine/Runtime/UI/Elements/PauseButton.cs

@@ -0,0 +1,22 @@
+using NaughtyAttributes;
+using UnityEngine;
+using UnityEngine.UI;
+
+namespace EscapeRoomEngine.Engine.Runtime.UI.Elements
+{
+    /// <summary>
+    /// This component is responsible to change the icon of the pause button depending on the game state.
+    /// </summary>
+    public class PauseButton : MonoBehaviour
+    {
+        [BoxGroup("Internal")] [SerializeField]
+        private Image icon;
+        [BoxGroup("Internal")] [SerializeField]
+        private Sprite pauseIcon, resumeIcon;
+
+        public bool Paused
+        {
+            set => icon.sprite = value ? resumeIcon : pauseIcon;
+        }
+    }
+}