feat(storybook): add a11y test runner

[geromegrignon]

PR Checklist

Please check if your PR fulfills the following requirements:

• [x] The commit message follows our guidelines: https://github.com/realworld-angular/realworld-angular-starter/blob/main/CONTRIBUTING.md
• [x] Tests for the changes have been added (for bug fixes / features)
• [ ] Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• [ ] Bugfix
• [x] Feature
• [ ] Code style update (formatting, local variables)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] CI related changes
• [ ] Documentation content changes
• [ ] Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Add a11y test runner

Does this PR introduce a breaking change?

• [ ] Yes
• [ ] No

Other information

[netlify[bot]]

✅ Deploy Preview for realworld-angular-starter ready!

Name	Link
🔨 Latest commit	f6d9ca17ec770628fc5905954255c1a8fd250dc3
🔍 Latest deploy log	https://app.netlify.com/sites/realworld-angular-starter/deploys/66b155bab4bce80008151592
😎 Deploy Preview	https://deploy-preview-11--realworld-angular-starter.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[netlify[bot]]

✅ Deploy Preview for storybook-realworld-angular ready!

Name	Link
🔨 Latest commit	f6d9ca17ec770628fc5905954255c1a8fd250dc3
🔍 Latest deploy log	https://app.netlify.com/sites/storybook-realworld-angular/deploys/66b155ba501d68000848740c
😎 Deploy Preview	https://deploy-preview-11--storybook-realworld-angular.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.