Release Tooling Project: Build GH Action that creates/updates a Preelease PR

[JReinhold]

This action will create and keep a release branch+PR up-to-date.

• Triggers: pushes to next and manual
• Inputs to workflow_dispatch: tag (alpha, beta, rc, stable)
• Abort early if an existing Release PR has "freeze" label
• Run check-release-needed.ts, verson.ts, write-changelog.ts
• Abort late if an existing Release PR has "freeze" label
• Create version-from-7.1.0-alpha.16 branch and force push
• Create or update existing PR pointing to next-release, with generate-pr-description.ts

[JReinhold]

This is pretty far. The remaining work needs #22601 and #22610

See current PR output at storybookjs#22 triggered by https://github.com/storybookjs/monorepo-release-tooling-prototype/actions/workflows/prepare-prerelease.yml