Expose focus events' types on MenuItem

[damianstasik]

Partially adresses #7453

Since MenuItem already passes onFocus, onBlur, and onFocusChange props directly to the useFocus hook, it would be great to explicitly expose the corresponding event types on MenuItem’s props interface.

✅ 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:

Try it out in the Menu's story.

🧢 Your Project:

None

[snowystinger]

Thanks for the PR, would you be willing to add some tests? https://react-spectrum.adobe.com/contribute.html#pull-requests