doc: document URLPattern instance getters

[charpeni]

URLPattern instances expose the protocol, username, password, hostname, port, pathname, search and hash getters, which return the pattern string of each component, and the hasRegExpGroups getter. They are implemented in src/node_url_pattern.cc, were part of the initial URLPattern implementation that shipped in v23.8.0, and are defined by the URL Pattern Standard, but doc/api/url.md never documented them.

This adds one subsection per getter to the URLPattern class section, placed before exec() and test() to mirror the layout of the URL class, each with the added: v23.8.0 metadata and a short example.

Every example output was verified by running the example code on v24.19.0.

Note

Disclosure per the AI use policy: Claude Fable 5.1 (Anthropic), running in Claude Code, was used to audit this page and draft the change. I reviewed the diff and verified the output myself, and I will handle review feedback personally.

Refs: https://urlpattern.spec.whatwg.org/#dom-urlpattern-hasregexpgroups

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