Ensure checkboxes without explicit values render no value attribute in the DOM

[brandonpittman]

This handles the issue with default checkboxes getting values of '' instead
of 'on' as noted here.

• Fix useToggle value when undefined
• Add tests for default checkbox values

Closes #3519

✅ 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:

Create checkbox without an explicit value and check that there's no value
attribute attached to it in the DOM.

🧢 Your Project:

Splink Inc.

[snowystinger]

Thanks for the PR! I added a test to Switch as well.

[LFDanLu]

LGTM