Menu is missing explicit content-box on unavailable icon

[dsmmcken]

Provide a general summary of the issue here

Similar to #6470 and #7456 when a Menu is marked as unavailable it gets a contextual help InfoOutline icon, if border-box is set in the a global reset, the icon doesn't show.

https://react-spectrum.adobe.com/react-spectrum/Menu.html#unavailable-items

🤔 Expected Behavior?

Icon should be visible

😯 Current Behavior

Icon is not shown.

💁 Possible Solution

This icon doesn't have an explicit box-sizing: content-box; which was added for chevron and checkmark, but missed on the InfoOutline icon. Add a class for the InfoOutline and add it to the icon.

🔦 Context

No response

🖥️ Steps to Reproduce

See reproduction steps in #6470 but use isUnavailable.

Version

3.21.0

What browsers are you seeing the problem on?

Chrome

If other, please specify.

No response

What operating system are you using?

Linux

🧢 Your Company/Team

No response

🕷 Tracking Issue

No response

[yihuiliao]

Seems reasonable to me given that we've done this in other components. Opened a PR #7572