[2.x] Semantic Tailwind Markdown heading permalinks

[emmadesilva]

• Part of [2.x] Custom Markdown heading renderer #2047
• Also refactors to use Tailwind instead of CSS

Advantages:

• Cleaner semantics: The id directly ties to the heading itself, which aligns well with HTML5 standards.
• Improved accessibility: Assistive technologies can better associate the id with the heading content.
• CSS styling: Easier to target headings via their id for custom styles.

See #2047 (comment)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (3d3ed48) to head (9c49d46).
Report is 11 commits behind head on custom-markdown-heading-renderer.

Additional details and impacted files

@@                         Coverage Diff                          @@
##             custom-markdown-heading-renderer     #2052   +/-   ##
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  Coverage                              100.00%   100.00%           
  Complexity                               1928      1928           
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  Files                                     196       196           
  Lines                                    5125      5125           
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  Hits                                     5125      5125           

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