Storybook

[inyono]

Includes a couple of quality of (developer) life changes (that also enable testing of the rendering entry points we discussed @Knorrke coming in another PR):

• Reconfigures prettier according to the existing file structure and runs it as a precommit git hook (as in serlo abc)
• Adds Storybook that replaces the current example page (since it's more flexible). We still have a story for the previous example page and stories for the existing plugins (w/ helpers for that, see index.stories.js in the plugin folders)

[inyono]

Kinda misleading: +3,988 −23,684 😅

[inyono]

Removed the unnecessary {' '}