feat: WAI-ARIA 1.3 Roles Model Support

[jlp-craigmorten]

This issue is to track supporting the WAI-ARIA 1.3 Roles Model.

This project currently purports to track WAI-ARIA 1.2 Roles Model but already has started to implement fixtures for WAI-ARIA 1.3, e.g. the mark role has made it's way into the fixtures despite being new as of 1.3, as have other attributes etc.

See https://www.w3.org/TR/wai-aria-1.3/#changelog for the 1.3 changelog.

It would be grand to have guidance whether we continue in this fashion and look to track WAI-ARIA 1.3 for the remainder of new roles and attributes, or if we consider 1.3 a new major for this project?

If the latter would be good to understand if we should revert any 1.3 specific fixtures in this project so that it accurately tracks 1.2?