ext/dom: Add global registerNodeNS flag on DOMXPath.

[beberlei]

PHP's DOMXpath automatically registers namespaces for xpath, which can be disabled with arguments $registerNodeNS to evaluate() and query() that defaults to true.

With this PR you can set this flag on the constructor as second argument of the xpath object globally for all evaluate/query calls: 😆

$xpath = new DOMXPath($doc, false);

In addition you can also use a property to read and write this value 🚀

$xpath = new DOMXPath($doc);
$xpath->registerNodeNamespaces = true;

Both approaches are needed, because the option is reasonably important to be set directly in the constructor, but also code that is "downstream" of the actual construction of DOMXPath may need to inspect or modify the setting before use. Without knowing which value this property has at the call site of query/evaluate it would cause problems.

Setting the $registerNodeNS argument on query/evaluate methods will overwrite the default options.

Fixes https://bugs.php.net/bug.php?id=55700

[beberlei]

Related: https://github.com/php/php-src/pull/779/files - is a public property better than a constructor param?

[beberlei]

Ok, I think while the constructor is the best way to configure this, without a property code that has no access to the constructing site (dependency inversion) might need to find out what mode the DOMXpath instance is in. So we need a property anyways. I think i will be going to add both and make the property read-only.

[beberlei]

Fixed in 6c96369