chore: speed up markdown docs script

[reidbarber]

The markdown docs generation script (yarn workspace @react-spectrum/s2-docs generate:md) was pretty slow due to repetitive sync glob and file reads. Now, we build an index of symbols and read from that instead.

On my machine:

Before: 113s
After: 5s

Also includes some improvements to the markdown output in some areas where we had gaps:

• fixed missing jsdoc descriptions
• fixed union type member ordering to be consistent (and match docs)
• added function signatures in Related Types

✅ 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:

Smoke test markdown docs outputs.

🧢 Your Project:

[rspbot]

Build successful! 🎉

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

[snowystinger]

I ran the command yarn workspace @react-spectrum/s2-docs generate:md on main and then on this branch (which appears to be up to date with main)

The output is different for the md files. I ran diff -r /Users/robsnow/Desktop/dist-main /Users/robsnow/Desktop/dist-new to verify

It looks like the new md files contain a lot more information? (although that any seems wrong in the function signature)

Also, sometimes the order of the values changes? I had to sort for tsdiffer otherwise it was random to an extent.

[rspbot]

Build successful! 🎉

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

[rspbot]

Build successful! 🎉

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

[reidbarber]

@snowystinger Thanks for checking that! Fixed the any issue and stabilized the union member ordering. Everything else should be an improvement (fixed some missing descriptions).