doc: anchor link parity between markdown and html-generated docs

Main changes:

- Replace current HTML anchor generation to match
  header anchor generation in Github markdown.
- Remove unnecessary double namespacing on generated anchors/links (E.G.
  `esm.md#loaders` instead of `esm.md#esm_loaders`).
- Anchors/links are automatically prefixed with their respective modules
  when concatenated for usage in `all.html`.

Benefits:

- All anchor links within and between markdown API docs actually work.
- Adding new anchor links no longer requires contributors to generate
  the HTML docs first to look up the correct anchors.
- Anchors are much shorter.
- All previous anchor links are preserved by generating hidden legacy
  anchors.

PR-URL: https://github.com/nodejs/node/pull/39304


Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>