Linter: Consider renaming all accessibility-related rule names to `a11y-*`

[marcoroth]

Currently, most accessibility-related rules have the prefix html-* as we only have been really differentiating between html-*, erb-* and svg-*.

Maybe it would make sense to categorize/namespace the accessibility-related rules have the a11y-* prefix to make it more obvious.

We also have been slowly introducing herb-* and turbo-* as prefixes, and I think some rules could also benefit from other namespaces like actionview-*, actionmailer-*, stimulus-* etc.

Related: #1066

[written-fresh]

Wonder if it would be worth putting a doc together outlining all of these?

[marcoroth]

@written-fresh yeah, I think we need to do a pass to go over them all at once. Since we also need to handle the redirection logic, and making sure if people disabled the rule with their old name that they have a migration path.

Though, for new rules we can already start using the new a11y-* prefix so we don't have to rename them later.