Storybook: Add addon-docs and configure for Wildcard components

Created by: umpox

This PR implements @storybook/addon-docs across our Storybook stories.

This will help us achieve the goal of better documenting Wildcard components whilst also improving the documentation of the rest of our current components.

It aggregates the stories onto a single page, and automatically infers documentation through types and JSDoc comments.

Demo

Closes https://github.com/sourcegraph/sourcegraph/issues/23080