Add gap to progressbar with multiple sections

[lukasoppermann]

This bug was mentioned in slack and is apparent when looking at the docs.

Expected
When a progressbar has multiple sections, a 2px gap is shown between them.

Current behavior
When a progressbar has multiple sections, a no gap is shown between them. making them sometimes very hard to distinguish.

Changelog

• added a 2opx gap when the Progressbar component has children.

Before	After

• added sections control to the playground story to allow users to check the difference.

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: 4283297

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	Patch

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[github-actions]

size-limit report 📦

Path	Size
packages/react/dist/browser.esm.js	97.46 KB (+0.1% 🔺)
packages/react/dist/browser.umd.js	97.68 KB (-0.12% 🔽)

[TylerJDev]

Left a comment to fix the gap property not being applied, but otherwise looks good!

[siddharthkp]

I see 2 suggestions, other than that. All good!

Approving in advance