fix(focus): add permisison element to focusable elements list

[gabrielchl]

Closes #8226

✅ Pull Request Checklist:

• Included link to corresponding React Spectrum GitHub Issue.
• Added/updated unit tests and storybook for this change (for new code or code which already has tests).
• Filled out test instructions.
• Updated documentation (if it already exists for this component).
• Looked at the Accessibility Practices for this feature - Aria Practices

📝 Test Instructions:

• change contain={contain} to contain at packages/@react-aria/focus/stories/FocusScope.stories.tsx:61
• add <permission type="microphone"></permission> to packages/@react-aria/focus/stories/FocusScope.stories.tsx:66
• in Chrome Beta, visit http://localhost:9003/?path=/story/focusscope--keyboard-navigation-no-contain and verify that the permission element can now be tabbed to and away from

🧢 Your Project:

before (when tab/shift-tab-ing, it skips over the permission element):

after (able to navigate to the permission element via keyboard, and activate the element):

[reidbarber]

Thanks!!

[reidbarber]

Looks like you'll need to Sign the CLA, then close and re-open this PR to trigger another build that passes.