Compare ymllint to Prettier

[james-garriss]

💡 Summary

What is the work, as a high-level summary?

There is a GitHub Action workflow that lints YAML files, and it uses ymllint under the covers. Most of the developers on the team code with VS Code, which uses Prettier by default for linting YAML file. Wouldn't it be nice if the workflow used the same tool that the developers use?

Motivation and context

Why does this work belong in this project?

It would slightly ease the burden of development.

ymllint is not broken, and the extent to which the two tools have different linting rules is unknown. This could be explored during this issue. Perhaps ymllint is better; perhaps not.

Implementation notes

Please provide details for implementation, such as:

• Compare and contrast the linters
• Select one as "better"
• If Prettier, then replace ymllint with Prettier. This should be easy, as MegaLinter supports both.

Acceptance criteria

How do we know when this work is done?

• [ ] Prettier is successfully linting YAML files whenever a YAML file is pushed to the repo.

[james-garriss]

I've been looking for yamllint as a VSCode extension. The authors of yamllint recommend using this extension:
https://marketplace.visualstudio.com/items?itemName=fnando.linter

If we can all agree to use that, then this issue (763) becomes moot. OTOH, if we switch everything to Prettier, then there's no need for devs to add this extension.