feat(html): section-collapse metadata

[benlubas]

Collapse (hide) sections (delimited by headings) by clicking a chevron next to the heading. Expand/collapse all with an option in the codetools menu

Description

New front-matter config for the HTML format section-collapse. Inspired by the old jupyter-contrib-nbextension: Collapsible headings

• when true: creates chevrons on the right of all headers, when clicked they "collapse" and hide all of their content
• when false: does nothing
• when closed start closed

Additionally:

• make the "code tools" menu multi-purpose. The name is displayed as "Tools" instead of "Code" when it's showing any non-code-related menu item
• Add section code-tools key which controls the addition of "expand/collapse all sections" buttons

Now that I'm opening the PR section-fold might make more sense, and we can change the behavior to mimic code-fold (true: closed, "show": open with option to fold). lmk if you prefer that.

screen shots

Checklist

I have (if applicable):

• filed a contributor agreement.
• referenced the GitHub issue this PR closes (you guys don't like feature request issues, so I didn't make one)
• updated the appropriate changelog in the PR
• ensured the present test suite passes
• added new tests
• created a separate documentation PR in Quarto's website repo and linked it to this PR (metadata documentation is autogenerated from yaml, right? I added descriptions in the yaml)

[posit-snyk-bot]

✅ Snyk checks have passed. No issues have been found so far.

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✅	Licenses	0	0	0	0	0 issues

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[benlubas]

These test failures don't appear to be related to my PR? The error for them doesn't even make sense: "2.0 is not 2.0"