fix(@react-stately/date): update parentKey when a tree node is moved to another parent

[alirezamirian]

closes #1987

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:

Can't think of any necessary manual testing.

[dannify]

Thanks @alirezamirian 🤩 We will take a look

[LFDanLu]

LGTM, thanks for the catch!

[snowystinger]

lgtm