Add escape key handlers to open accordions and its inner content

[rezrah]

Summary

Resolves #519

List of notable changes:

• adds esc key press handler to open accordions titles, which both closes them and returns focus
• adds esc key press handler to accordion content elements, which both closes the accordion and returns focus to the nearest toggle ancestor.

What should reviewers focus on?

• Verify that the escape key event works as expected to close the accordions, whether it's on the toggle itself or inner link.

Steps to test:

1. Open this story
2. Use keyboard navigation to focus on a accordion summary
3. Open accordion details using space or enter keys
4. Press escape to close the accordion details
5. Optionally test inner link contained in details, which should similarly close the accordion and return focus

Supporting resources (related issues, external links, etc):

• https://github.com/github/accessibility-audits/issues/7115

Contributor checklist:

• All new and existing CI checks pass
• Tests prove that the feature works and covers both happy and unhappy paths
• Any drop in coverage, breaking changes or regressions have been documented above
• New visual snapshots have been generated / updated for any UI changes
• All developer debugging and non-functional logging has been removed
• Related issues have been referenced in the PR description

Reviewer checklist:

• Check that pull request and proposed changes adhere to our contribution guidelines and code of conduct
• Check that tests prove the feature works and covers both happy and unhappy paths
• Check that there aren't other open Pull Requests for the same update/change

Screenshots:

Escape key press event on accordion summaries:

Kapture.2024-01-23.at.13.43.44.mp4

Escape key press events on internal links on open accordions:

Kapture.2024-01-23.at.13.45.19.mp4

[changeset-bot]

🦋 Changeset detected

Latest commit: d1ec238

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

This PR includes changesets to release 6 packages

Name	Type
@primer/react-brand	Patch
@primer/brand-primitives	Patch
@primer/brand-e2e	Patch
@primer/brand-fonts	Patch
@primer/brand-config	Patch
@primer/brand-storybook	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

🟢 No design token changes found

[github-actions]

🟢 No visual differences found

Our visual comparison tests did not find any differences in the UI.