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

packages/grafana-ui/package.json

@@ -53,6 +53,7 @@
     "clean": "rimraf ./dist ./compiled ./unstable ./package.tgz",
     "storybook": "storybook dev -p 9001 -c .storybook --no-open",
     "storybook:build": "storybook build -o ./dist/storybook -c .storybook",
+    "storybook:test": "test-storybook --url http://localhost:9001",
     "typecheck": "tsc --emitDeclarationOnly false --noEmit",
     "prepack": "cp package.json package.json.bak && ALIAS_PACKAGE_NAME=unstable node ../../scripts/prepare-npm-package.js",
     "postpack": "mv package.json.bak package.json && rimraf ./unstable"
@@ -152,6 +153,7 @@
     "@storybook/preview-api": "^8.6.2",
     "@storybook/react": "^8.6.2",
     "@storybook/react-webpack5": "^8.6.2",
+    "@storybook/test-runner": "^0.23.0",
     "@storybook/theming": "^8.6.2",
     "@testing-library/dom": "10.4.0",
     "@testing-library/jest-dom": "6.6.3",