[Discover] Tabs - a11y improvements

[MiloszRadzynski]

Summary

This PR enables keyboard navigation for tabs in Discover. Users are now able to:

• Switch between tabs using arrow keys (when the entire tab is focused).
• Tab into the tab, and then focus the action menu and close button.
• Open the action menu while the icon is focused, using the Space or Enter key.
• Close the tab while the close icon is focused, using the Space or Enter key.
• Navigate to the first/last tab using the Home and End keys.

This change also improves the screen reader output for individual tabs within the tablist. Previously, the screen reader would announce the tab with the information: ...group, 1 of 1, even when the user had multiple tabs open. Now, the screen reader should properly announce the tab's position within the tab list. (see screenshots).

Screenshots:

Before:

After:

Checklist

Check the PR satisfies following conditions.

Reviewers should verify this PR satisfies this list as well.

• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios
• If a plugin configuration key changed, check if it needs to be allowlisted in the cloud and added to the docker list
• This was checked for breaking HTTP API changes, and any breaking changes have been approved by the breaking-change committee. The release_note:breaking label should be applied in these situations.
• Flaky Test Runner was used on any tests changed
• The PR description includes the appropriate Release Notes section, and the correct release_note:* label is applied per the guidelines
• Review the backport guidelines and apply applicable backport:* labels.

[MiloszRadzynski]

/ci

[akowalska622]

Great changes, LGTM thanks!

[elasticmachine]

Pinging @elastic/kibana-data-discovery (Team:DataDiscovery)

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 0801c4c

Metrics [docs]

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
discover	1.3MB	1.3MB	+202.0B
lens	1.6MB	1.6MB	+208.0B
total			+410.0B

History

• 💛 Build #368298 was flaky b7b817d

cc @MiloszRadzynski