Add new pricing options component

[danielguillan]

Summary

Part of https://github.com/github/primer/issues/2954

Adds new pricing options component.

🔗 Documentation
🔗 Storybook

📋 Todo

• Fix one item layout
• Increase test coverage
• Add Default story
• Add visual snapshots
• Add changeset
• Add documentation
• Update pricing format with currency code
• Add collapsible feature set on small viewports

List of notable changes:

• added pricing options component

What should reviewers focus on?

Steps to test:

1. Use this storybook link and review the individual stories and playground
2. Use this documentation link to read through public docs

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
• New visual snapshots have been generated / updated for any UI changes
• 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

Screenshots:

[changeset-bot]

🦋 Changeset detected

Latest commit: 919fd01

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

This PR includes changesets to release 6 packages

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

🟢 No design token changes found

[github-actions]

⚠️ Visual differences found

Our visual comparison tests found UI differences.

Please review the differences by using the test artifacts to ensure that the changes were intentional.

Artifacts can be downloaded and reviewed locally.

Download links are available at the bottom of the workflow summary screen.

Example:

If the changes are expected, please run npm run test:visual:update-snapshots to replace the previous fixtures.

Review visual differences

[rezrah]

Can this be done as a progressive enhancement, where using subgrid is optional and opt-in? Looks like it's the other way around right now, which might not fly with house rules. That said, this is much nicer for balancing our tech debt.

[danielguillan]

I implemented the progressive enhancement approach initially but chose this route because:

1. It's as safe as the progressive enhancement: the @supports at-rule is supported on all our supported browsers 🤪, which ensures everyone is getting the "baseline" behavior
2. It is much simpler and easier to read than the progressive enhancement implementation. And we can delete the whole statement when subgrid is fully supported.

[rezrah]

Very nice work @danielguillan. It's a big PR, so I've focussed on providing critical path feedback only so we can get this out today. Anything extra can be updated in follow up PR's or uncovered during smoke tests.