Adds UnderlinePanels to drafts/

[mperrotti]

Relates to https://github.com/github/primer/issues/3108

This component is visually identical to UnderlineNav. The biggest differences are:

• These are tabs as behave as such
• It cannot be used as a controlled component
• No responsive overflow menu (issue)

Kapture.2024-05-01.at.16.34.03.mp4

Changelog

New

Adds UnderlinePanels component

Changed

Refactors UnderlineNav to share component styles with UnderlinePanels

Removed

Nothing 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

This should more or less behave like PVC's UnderlinePanels

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: 1cbc162

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

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

[mperrotti]

Added @keithamus as a reviewer since he's familiar with @github/tab-container-element, which does a lot of the heavy-lifting here.

[github-actions]

size-limit report 📦

Path	Size
packages/react/dist/browser.esm.js	90.88 KB (+0.29% 🔺)
packages/react/dist/browser.umd.js	91.07 KB (+0.2% 🔺)