markdown: Move `open_url` to the `MarkdownElement` as `on_url_click` (#28269)

Release Notes:

- N/A

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Co-authored-by: Antonio Scandurra <me@as-cii.com>
0414908c4aMarshall Bowers committed on 4/7/2025, 8:43:00 PM· committed by GitHubparentd3abc61
6 files changedLine totals unavailable