Add choice element rendering in documentation

[mretegan]

This PR adds support for rendering <choice> elements in the HTML documentation and ensures that all elements (fields, groups, choices, links) are rendered in their original XML document order. Closes #1439

[woutdenolf]

@PeterC-DLS Any idea why the CI does not get executed?

[PeterC-DLS]

We have chosen to set the Approval rule for running fork PR workflows to "Only users who have never had a commit or pull request merged into this repository will require approval to run workflows" - see (https://docs.github.com/en/actions/how-tos/manage-workflow-runs/approve-runs-from-forks)

[woutdenolf]

I don't seem to have permissions to give approval unless I'm missing something.

[PeterC-DLS]

Perhaps they can try rebasing it

[woutdenolf]

The "choice" docs are now showing up like this:

[woutdenolf]

Apart from refactoring the way we extract tag names (group, field, attribute, link, choice) from XML nodes it looks good.

Edit: I'll refactor the tag stuff in another PR. #1624

[woutdenolf]

@PeterC-DLS This is a fix for showing choice tags in the HTML docs. Do you mind we merge this before the patch release or wait till after (better safe than sorry)?

[PeterC-DLS]

This fails for me on rebasing to the main branch owing to the bug fixed in #1608

[mretegan]

@PeterC-DLS I synchronized the branch with the current state of main.

[PeterC-DLS]

LGTM