[GIT-PULLS] [php-src] PR #23498: [DOM] Fix getNamedItemNS() with empty URI not matching null namespace

Pull Request: https://github.com/php/php-src/pull/23498
Author: iliaal

Dom\NamedNodeMap::getNamedItemNS() passed an empty-string URI straight to xmlHasNsProp(), which matches NULL-namespace attributes only when the URI pointer is NULL, so getNamedItemNS("", "bar") returned NULL even though hasAttributeNS("", "bar") found the attribute in spec-following mode. An empty URI now normalizes to NULL at the namednodemap entry point when a base object is present, the same conversion dom_get_attribute_ns() applies in element.c. A sibling audit of xmlHasNsProp() and xmlGetNsProp() call sites found no other path passing a user-supplied URI.