Add new @primer/brand-css package

[rezrah]

Summary

Closes https://github.com/github/primer/issues/3658

List of notable changes:

What should reviewers focus on?

Steps to test:

Supporting resources (related issues, external links, etc):

Contributor checklist:

• All new and existing CI checks pass
• Tests prove that the feature works and covers both happy and unhappy paths
• Any drop in coverage, breaking changes or regressions have been documented above
• UI Changes contain new visual snapshots (generated by adding update snapshots label to the PR)
• All developer debugging and non-functional logging has been removed
• Related issues have been referenced in the PR description

Reviewer checklist:

• Check that pull request and proposed changes adhere to our contribution guidelines and code of conduct
• Check that tests prove the feature works and covers both happy and unhappy paths
• Check that there aren't other open Pull Requests for the same update/change

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Before	After

[changeset-bot]

🦋 Changeset detected

Latest commit: 33fdd1b

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

This PR includes changesets to release 7 packages

Name	Type
@primer/brand-css	Minor
@primer/react-brand	Minor
@primer/brand-primitives	Minor
@primer/brand-e2e	Minor
@primer/brand-fonts	Minor
@primer/brand-config	Minor
@primer/brand-storybook	Minor

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[github-actions]

🟢 No design token changes found

[github-actions]

🟢 No visual differences found

Our visual comparison tests did not find any differences in the UI.

[joshfarrant]

Excuse the review of a Draft, but spotted this and wanted to mention before I forgot 🙂

[joshfarrant]

Maybe this would be a little bit more robust going forward?

Suggested change

	entry.name.endsWith('.module.css') &&
	!entry.name.includes('stories') &&
	!entry.name.includes('features')
	/^\w+\.module\.css$/.test(entry)

That matches abc.module.css but not abc.xyz.module.css. wdyt?

[rezrah]

Do we need to match abc.xyz.module.css? 🤔

[joshfarrant]

Hmm, I didn't think so, I thought all of our main CSS was stored in the abc.module.css file.

I was only thinking that a rogue css file could make its way in to the library if it doesn't contain stories or features. If you'd prefer it this way round though feel free to disregard this.