use new pipeline and htlengine for full jsdom support

[tripodsan]

The improved pipeline now only uses JSDOM. The DOM supporting htlengine can directly use the prepared document thus avoiding to/from HTML serialization roundtrips.

Note the breaking changes:

BREAKING CHANGES:

• remove htast from context.content schema
• remove hast from context.response schema
• add document from to context.response schema
• context.htast and context.response.hast is no longer generated
• mdast to jsdom transformation handlers can only return hast (not string, not vdom)
• html postprocessing pipeline step was renamed from hast to post
• mixing inline html and markdown no longer works (eg: <em>This is **strong**</em>)

---

• see use jsdom throughout the pipeline and use jsdom supporting htl engine helix-pipeline#337
• see improve vdom generator performance helix-pipeline#336
• see https://github.com/adobe/htlengine/releases/tag/v3.0.0

[adobe-bot]

🎉 This issue has been resolved in version 4.2.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀