feat: refactor the arr helper class, add new util method

Author: inhere

src/Arr/ArrConst.php

@@ -0,0 +1,15 @@
+<?php declare(strict_types=1);
+
+namespace Toolkit\Stdlib\Arr;
+
+/**
+ * class ArrConst
+ *
+ * @author inhere
+ * @date 2022/12/30
+ */
+class ArrConst
+{
+    public const FLAT_DOT_JOIN_INDEX = 1;
+
+}