chore: Deploy storybook automatically, without relying on build artifacts in repo

[henningmu]

Closes #252 Part of https://github.com/Doist/reactist/issues/675

Short description

Previously, one would be required to run npm run build-all and commit the updated files from docs/ folder to this repository. This made reviews harder, was cumbersome and error-prone. With this PR, it's a thing of the past. We're now building and deploying the storybook from a GitHub Action on each commit on main. Proper CD if you will 💫

[gnapse]