Use antsibull-docutils 1.2.0 to simplify rst-yamllint checker

[felixfontein]

I added code to antsibull-docutils to allow enumeration of code blocks in RST files, based on the code of this repo's rst-yamllint checker. This got released in antsibull-docutils 1.2.0. (I'm using it to provide similar checks for antsibull-nox.)

This PR adjusts the rst-yamllint checker to use antsibull-docutils. This simplifies the checker considerably (no handling of docutils needed anymore!).

[samccann]

@felixfontein sorry for the delay here. Looks like it needs a rebase now. We've also been asked if we can add xml to the LANGUAGES. Do you know if that's as simple as just adding it to the existing LANGUAGES list in rst-yamllint file?

[felixfontein]

We've also been asked if we can add xml to the LANGUAGES. Do you know if that's as simple as just adding it to the existing LANGUAGES list in rst-yamllint file?

If you mean ALLOWED_LANGUAGES, then yes, you can simply add it there to allow it.

[oraNod]

This looks great to me. Gets rid of a bunch of custom stuff and simplifies things so thank you @felixfontein

[felixfontein]

I rebased since #2807 introduced a conflict.

[patchback]

Backport to stable-2.19: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 51ee33e on top of patchback/backports/stable-2.19/51ee33e26353be7c6be2736c99e1e412745a93b1/pr-2745

Backporting merged PR #2745 into devel

1. Ensure you have a local repo clone of your fork. Unless you cloned it
   from the upstream, this would be your origin remote.
2. Make sure you have an upstream repo added as a remote too. In these
   instructions you'll refer to it by the name upstream. If you don't
   have it, here's how you can add it:

   $ git remote add upstream https://github.com/ansible/ansible-documentation.git

3. Ensure you have the latest copy of upstream and prepare a branch
   that will hold the backported code:

   $ git fetch upstream
   $ git checkout -b patchback/backports/stable-2.19/51ee33e26353be7c6be2736c99e1e412745a93b1/pr-2745 upstream/stable-2.19

4. Now, cherry-pick PR Use antsibull-docutils 1.2.0 to simplify rst-yamllint checker #2745 contents into that branch:

   $ git cherry-pick -x 51ee33e26353be7c6be2736c99e1e412745a93b1

   If it'll yell at you with something like fatal: Commit 51ee33e26353be7c6be2736c99e1e412745a93b1 is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 51ee33e26353be7c6be2736c99e1e412745a93b1

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Use antsibull-docutils 1.2.0 to simplify rst-yamllint checker #2745 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/stable-2.19/51ee33e26353be7c6be2736c99e1e412745a93b1/pr-2745

7. Create a PR, ensure that the CI is green. If it's not — update it so that
   the tests and any other checks pass. This is it!
   Now relax and wait for the maintainers to process your pull request
   when they have some cycles to do reviews. Don't worry — they'll tell you if
   any improvements are necessary when the time comes!

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

[felixfontein]

@oraNod thanks for reviewing this one as well!