Closes GH-20354

…rySelectorAll requires elements in $selectors to be lowercase (#20409)

The selector needs to be compared in a lowercase manner.
This also almost completely obsoletes the interned string optimization,
so get rid of that for simplicity sake. While there is still theoretical
benefit, it is only 1-2% in my random tests, not worth it anymore.

These are only useful on Unix-like environments when libmm is enabled
via configuration option.

* PHP-8.4:
  Fix GH-20395: \Dom\ParentNode::querySelector and \Dom\ParentNode::querySelectorAll requires elements in $selectors to be lowercase (#20409)

* PHP-8.5:
  Fix GH-20395: \Dom\ParentNode::querySelector and \Dom\ParentNode::querySelectorAll requires elements in $selectors to be lowercase (#20409)