chore: Replace deprecated mozInputSource check for virtual click detection

[LFDanLu]

Closes

✅ 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:

Test that virtual clicks are still properly detected for JAWS/NVDA, sanity check other screenreader/browser combinations.
To test, can try the drag and drop stories and attempt keyboard drag and drop

🧢 Your Project:

RSP

[rspbot]

Build successful! 🎉

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