Add main menu, loding screen and loding logic

Assets/Scripts/LoaderCallback.cs

@@ -0,0 +1,20 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+public class LoaderCallback : MonoBehaviour
+{
+
+    private bool isFirstUpdate = true;
+
+    private void Update()
+    {
+        if (isFirstUpdate)
+        {
+            isFirstUpdate = false;
+
+            Loader.LoaderCallback();
+        }
+    }
+
+}