Add aria-expanded back to AnchoredOverlay

[TylerJDev]

Will resolve: https://github.com/github/accessibility-audits/issues/6932

We have an open accessibility issue related to how we handle aria-expanded within AnchoredOverlay. We did not apply aria-expanded when a menu was open since it was redundant, and it was very unlikely that there'd be navigation outside of the menu before it was closed. We've received feedback that this may cause an unintended effect for users using specific devices/AT that makes it difficult to leave the menu.

Changelog

Changed

• Adds full aria-expanded state to AnchoredOverlay.

Rollout strategy

Integration test PR: https://github.com/github/github/pull/323711. There are some flakey tests that are failing which are not caused by this PR. The changes required for this PR are: https://github.com/github/github/pull/323711/commits/dd6a1dee058ee4659bb1ed36ac50e5356b3de832

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; if selected, include a brief description as to why

Testing & Reviewing

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github (Learn more about how to run integration tests)

[changeset-bot]

🦋 Changeset detected

Latest commit: 4b4e4ff

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@primer/react	Patch

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[github-actions]

size-limit report 📦

Path	Size
packages/react/dist/browser.esm.js	88.6 KB (+0.08% 🔺)
packages/react/dist/browser.umd.js	88.88 KB (+0.05% 🔺)

[lindseywild]

@TylerJDev Hi! Do you have an idea of when this will be merged? 🙏🏻

[TylerJDev]

@lindseywild, just needs to get reviewed now! I redid my integration test PR, and it looks good (outside of flakey tests). Requires some changes in GH for tests: https://github.com/github/github/pull/323711#issuecomment-2098990100.

cc: @primer/engineer-reviewers for a review 👀

[lindseywild]

@primer/engineer-reviewers Can someone please review this when you get a chance? Thanks!