Linter: group a11y-related rules

[markokajzer]

closes #1310

Group a11y-related rules together and change their prefix from html-* to a11y-*

I was looking at adding more a11y linter rules, so decided to do this cleanup first, so that they're all grouped together.

There might be some additional things that we need to do, as existing config might not work anymore for these rules. technically this is somewhat of a breaking change. what would be the preferred migration strategy?

• codemod for existing configs
• reading previous config keys (e.g. html-input-require-autocomplete)
• skip?
• ...?

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somewhat related question: i noticed that most of these only operate on html. however, with the introduction of #1350, their scope could be widened to include ERB tags as well.

is that something we would want to look into before introducing new rules? is that something we would want to pay attention to when introducing more a11y rules, like in #177?

[marcoroth]

Thanks @markokajzer!

I think I want to wait with this a little bit before we do a big rename of the linter rule names.

But I think for the migration story, we want to utilize the --upgrade command we introduced in #1453:

So that running herb-lint --upgrade will go through all files, renames any <%# herb:disable %> comments, and updates the .herb.yml from the old to the new rule names.

[markokajzer]

i'm happy to close this for now then 👍

i'll start adding new related rules under ally-* already, like ally-no-autofocus-attribute in #177 👍

if you want to look into handling of erb for some of these already existing ally rules, feel free to create a separate issue, and i can get going on that as well.

thank you mate! 🙏