Accessibility: Add storybook a11y tests that run in CI (#108543)

* add test runner and start experimenting with storybook a11y tests

* skip currently failing a11y tests

* first attempt at github action

* fix CODEOWNERS, fix copy assets

* no caching?

* make wait-on better

* increase timeout and add verbose logging

* kick CI

* remove verbose logging, try different runner

* remove commented out code in copyAssets

* try maxWorkers 2

* turn on verbose logging, run as part of same step

* test storybook verify

* try setting LANG

* tidy up

* add betterer test

.github/CODEOWNERS

@@ -999,6 +999,7 @@ embed.go @grafana/grafana-as-code
 /.github/workflows/publish-technical-documentation-release.yml @grafana/docs-tooling
 /.github/workflows/scripts/json-file-to-job-output.js @grafana/plugins-platform-frontend
 /.github/workflows/stale.yml @grafana/grafana-developer-enablement-squad
+/.github/workflows/storybook-a11y.yml @grafana/grafana-frontend-platform
 /.github/workflows/storybook-verification.yml @grafana/grafana-frontend-platform
 /.github/workflows/storybook-verification-playwright.yml @grafana/grafana-frontend-platform
 /.github/workflows/update-make-docs.yml @grafana/docs-tooling