Add altKey modifier to usePress hook events

[jeroenwienk]

Closes #2235

✅ 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:

In the story Button actions now fire with the altKey modifier in the event.

🧢 Your Project:

[devongovett]

Thank you!