docs: Refreshing GlobalHeader Storybook Example

[williamjstanton]

Summary

Fixes: none

The Storybook example GlobalHeader had some opportunities for improved accessibility.

1. Added accessible Tooltip to icon buttons
2. Replaced old SearchField with Combobox
3. Used AriaLiveRegion to demonstrate screen reader supported CountBadge
4. Updated style packages

Release Category

Documentation, Examples

Release Note

Optional release note message. Changelog and release summaries will contain a pull request title. This section will add additional notes under that title. This section is not a summary, but something extra to point out in release notes. An example might be calling out breaking changes in a labs component or minor visual changes that need visual regression updates. Remove this section if no additional release notes are required.

Checklist

• [ ] MDX documentation adheres to Canvas Kit's Documentation Guidelines
• [ ] Label ready for review has been added to PR

For the Reviewer

• [ ] PR title is short and descriptive
• [ ] PR summary describes the change (Fixes/Resolves linked correctly)
• [ ] PR Release Notes describes additional information useful to call out in a release message or removed if not applicable
• [ ] Breaking Changes provides useful information to upgrade to this code or removed if not applicable

Where Should the Reviewer Start?

Areas for Feedback? (optional)

• [ ] Code
• [ ] Documentation
• [ ] Testing
• [ ] Codemods

Testing Manually

Screenshots or GIFs (if applicable)

Thank You Gif (optional)