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___construct_error2.phpt

@@ -0,0 +1,22 @@
+--TEST--
+SPL: ArrayObject::__construct with too many arguments.
+--FILE--
+<?php
+echo "Too many arguments:\n";
+Class C implements Iterator {
+    function current(): mixed {}
+    function next(): void {}
+    function key(): mixed {}
+    function valid(): bool {}
+    function rewind(): void {}
+}
+
+try {
+  var_dump(new ArrayObject(new stdClass, 0, "C", "extra"));
+} catch (TypeError $e) {
+  echo $e->getMessage() . "(" . $e->getLine() .  ")\n";
+}
+?>
+--EXPECT--
+Too many arguments:
+ArrayObject::__construct() expects at most 3 arguments, 4 given(12)