[php-src] Issue #15591: DOMNodeList and DOMNamedNodeMap already (partially) implement ArrayAccess

Issue: https://github.com/php/php-src/issues/15591 Author: jnvsor ### Description ```php <?php $xml = <<<END <?xml version="1.0" encoding="UTF-8"?> <root> <child attribute="value" /> <child hello="world" /> </root> END; $doc = new DOMDocument(); $doc->loadXML($xml); assert($doc->firstChild->childNodes[3]->attributes['hello'] === $doc->firstChild->childNodes->item(3)->attributes->getNamedItem('hello')); assert($doc->firstChild->childNodes[3]->attributes['hello']->nodeValue === 'world'); ``` There doesn't seem to be any documentation indicating that DOMNodeList, DOMNamedNodeMap, and their php 8.4 Dom alternatives can be accessed like an array. According to https://3v4l.org/AGvek this has been the case since 5.6.3, but it isn't even documented in the 5.6.3 changelog The actual ArrayAccess interface isn't implemented on them because they don't have the methods, but it would be nice to see it in the documentation even if it means implementing them. ### PHP Version 8.3.9 ### Operating System _No response_