chore(SideNav): Add VRT tests

[JelloBagel]

Related to https://github.com/github/primer/issues/4132

Add VRT tests for SideNav using examples from https://primer.style/deprecated-components/side-nav/react/latest

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]

⚠️ No Changeset found

Latest commit: 1f9ca0e

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

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

[github-actions]

size-limit report 📦

Path	Size
packages/react/dist/browser.esm.js	102.51 KB (0%)
packages/react/dist/browser.umd.js	102.98 KB (0%)