[#64285] Upgrade to HTML-Pipeline 3

[myabc]

⚠️ this PR is based on #19036, #19028: please review/merge that work first.

Ticket

https://community.openproject.org/wp/64285

What are you trying to accomplish?

Upgrade our code base to use the latest version of HTML-Pipeline, v3.2.3

N.B. This is a significant upgrade - HTML-Pipeline has replaced Nokogiri with Selma (itself based on the Rust lol_html library), and while the authors claim performance benefits, there are some DOM manipulations that are no longer trivial (e.g. wrapping nodes).

The API for filters, sanitisation and Markdown processing has also changed significantly.

Screenshots

What approach did you choose and why?

Merge checklist

• [ ] Added/updated tests
• [ ] Added/updated documentation in Lookbook (patterns, previews, etc)
• [ ] Tested major browsers (Chrome, Firefox, Edge, ...)