fix: invalid HTML

[ahosgood]

Description

Fixes HTML validation

Specific Changes proposed

Added a role of "group" to all MenuButton components removes the HTML validation issue of:

An element with role=menuitemradio must be contained in, or owned by, an element with role=menubar or role=menu or role=group

...as MenuItem components can have a role.

Tested in https://validator.w3.org/ with the included sandbox example.

Requirements Checklist

• Feature implemented / Bug fixed
• If necessary, more likely in a feature request than a bug fix
  • Change has been verified in an actual browser (Chrome, Firefox, IE)
  • Unit Tests updated or fixed
  • Docs/guides updated
  • Example created (starter template on JSBin)
  • Has no DOM changes which impact accessiblilty or trigger warnings (e.g. Chrome issues tab)
  • Has no changes to JSDoc which cause npm run docs:api to error
• Reviewed by Two Core Contributors

[welcome]

💖 Thanks for opening this pull request! 💖

Things that will help get your PR across the finish line:

• Run npm run lint -- --errors locally to catch formatting errors earlier.
• Include tests when adding/changing behavior.
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We get a lot of pull requests on this repo, so please be patient and we will get back to you as soon as we can.

[opa26033]

Op bro,