ext/spl: Deprecate ArrayObject and ArrayIterator with objects (#19420)

RFC: https://wiki.php.net/rfc/deprecations_php_8_5#deprecate_arrayobject_and_arrayiterator_with_objects

This also moves tests into a subfolder.

ext/spl/tests/ArrayObject/arrayObject_clone_basic1.phpt

@@ -0,0 +1,48 @@
+--TEST--
+SPL: Cloning an instance of ArrayObject which wraps an array.
+--FILE--
+<?php
+$a = array(1,2);
+$aa1 =  new ArrayObject($a);
+$a['p1'] = 'new element added to a before clone';
+
+$aa2 = clone $aa1;
+
+$a['p2'] = 'new element added to a after clone';
+$aa1['new.aa1'] = 'new element added to aa1';
+$aa2['new.aa2'] = 'new element added to aa2';
+var_dump($a, $aa1, $aa2);
+?>
+--EXPECT--
+array(4) {
+  [0]=>
+  int(1)
+  [1]=>
+  int(2)
+  ["p1"]=>
+  string(35) "new element added to a before clone"
+  ["p2"]=>
+  string(34) "new element added to a after clone"
+}
+object(ArrayObject)#1 (1) {
+  ["storage":"ArrayObject":private]=>
+  array(3) {
+    [0]=>
+    int(1)
+    [1]=>
+    int(2)
+    ["new.aa1"]=>
+    string(24) "new element added to aa1"
+  }
+}
+object(ArrayObject)#2 (1) {
+  ["storage":"ArrayObject":private]=>
+  array(3) {
+    [0]=>
+    int(1)
+    [1]=>
+    int(2)
+    ["new.aa2"]=>
+    string(24) "new element added to aa2"
+  }
+}