[WIP]: add Agent Skill for S1 to S2 migration

[reidbarber]

Work in progress: This PR adds an Agent Skill that helps users upgrade from v3 to S2. TLDR is that it tells the agent how to effectively run the codemods, then fix everything the codemod couldn't fix automatically.

✅ 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:

Install the skill:

npx skills add https://d1pzu54gtk2aed.cloudfront.net/pr/631e45ad557b4ee1d6c9f980f9ab97b69aa9b54a/ --skill react-spectrum-v3-to-s2-migration

and invoke it when upgrading your project.

🧢 Your Project:

[rspbot]

Build successful! 🎉

• View the storybook
• View the S2 storybook
• View the S2 docs
• View the React Aria docs