Add className prop to FormControl

[iansan5653]

Closes #4823

Changelog

New

• Adds className prop to FormControl component

Changed

Removed

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; if selected, include a brief description as to why

Testing & Reviewing

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github (Learn more about how to run integration tests)

[changeset-bot]

🦋 Changeset detected

Latest commit: f5d6fce

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@primer/react	Minor

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

size-limit report 📦

Path	Size
packages/react/dist/browser.esm.js	95.89 KB (+0.1% 🔺)
packages/react/dist/browser.umd.js	96.21 KB (+0.02% 🔺)

[joshblack]

Thanks for adding this!