fix(appswitcher): firefox focus

[erzhan-temir-mamyrov]

GRAPHITE-63825

Summary

• Firefox only: disable focus on header panel menu when panel is closed

Change List (commits, features, bugs, etc)

• Add dynamic tabIndex for header panel menu when panel is closed
• Update snapshots

Acceptance Test (how to verify the PR)

• In Firefox
• Go to this story
• Enable Mac Voice Over or JAWS
• Put focus on App Switcher button
• Press tab one more time
• Verify that Screen Reader announces leaving the page and don't read panel menu items

Regression Test (how to make sure this PR doesn't break old functionality)

• tests here

Things to look for during review

• Make sure all references to iot or bx class prefix is using the prefix variable
• (React) All major areas have a data-testid attribute. New test ids should have test written to ensure they are not changed or removed.
• UI should be checked in RTL mode to ensure the proper handling of layout and text.
• All strings should be translatable.
• The code should pass a11y scans (The storybook a11y knob should show no violations). New components should have a11y test written.
• Unit test should be written and should have a coverage of 90% or higher in all areas.
• All components should be passing visual regression test. For new styles or components either a visual regression test should be written for all permutations or the base image updated.
• Changes or new components should either write new or update existing documentation.
• PR should link and close out an existing issue

[netlify]

✅ Deploy Preview for carbon-addons-iot-react ready!

Name	Link
🔨 Latest commit	bb0689b
🔍 Latest deploy log	https://app.netlify.com/sites/carbon-addons-iot-react/deploys/64abbe72b4e31700087ad913
😎 Deploy Preview	https://deploy-preview-3813--carbon-addons-iot-react.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.