refactor(project): update structure to monorepo

[joshblack]

RFC: https://github.com/github/primer/discussions/2955

This Pull Request is a proposal to demonstrate the project structure for the RFC for moving Primer React to a monorepo.

Checklist

• Structure
  • @primer/react added as workspace
  • docs added as workspace
  • examples added as workspaces
• Tooling
  • ESLint
  • TypeScript
  • Prettier
  • Markdownlint
  • Jest
  • Changesets
• GitHub Actions
  • Deploy Production
  • Deploy Preview
  • Deploy Preview forks
  • Release
  • Release Canary
  • Release Candidate
  • Size
  • CI
  • Update Snapshots
  • VRT
  • Consumer Test

Notes

• Due to docs, we need to have --legacy-peer-deps turned on by default
• Lack of hoisting options makes this process challenging 😅 it'd be great to use pnpm or yarn (specifically yarn v2+, not yarn v1)
  • For example, if we have a shared dependency (like mdx) that uses context then we require the package version to be the same across the monorepo (otherwise the contexts would be different and would not work)
• We could update our release canary step to only publish if a changeset is available in any package instead of forcing an individual package

Known issues

• The styles for docs seems to be off 🤔

Possible next steps

• Add documentation for common monorepo tasks
• Add more examples to the examples directory, in particular one for Next.js app router
• Refactor ad-hoc scripts under script to dedicated (internal) packages
• Add a "primer cli" that wraps common commands in the monorepo, in particular scaffolding different file types
• Explore alternate npm clients (such as pnpm, yarn) to help with dependency hoisting issues
• Explore monorepo tooling (such as nx, turbo, lerna) to help with common monorepo tasks

[changeset-bot]

⚠️ No Changeset found

Latest commit: d7b0fa9

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.

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[github-actions]

size-limit report 📦

Path	Size
dist/browser.esm.js	0 B (-100% 🔽)
dist/browser.umd.js	0 B (-100% 🔽)
packages/react/dist/browser.esm.js	112.95 KB (+100% 🔺)
packages/react/dist/browser.umd.js	113.61 KB (+100% 🔺)

[smockle]

Heads-up: This broke the “primer-react” workflow in code-stats-collector—the past 18 hours of workflow runs have failed. I opened https://github.com/github/code-stats-collector/pull/672 to fix the issue by updating the paths in the workflow.