Storybook integration

[wKich]

In the last brainstorm session for the H1 2021, we decided it is nice to have this feature for the BigTest. I still don't have enough context about the project, so I'd like to discuss this feature's details. How do you see it should be?

So how I see it.

It should be a third-party addon that reuses the interactors inspector #873 to show information about matched interactors and provide a place to play around with the interactor's actions.

Storybook allows reusing stories in unit tests. We could try to show tests and provide the ability to run them right in Storybook.

We might allow the user to record actions sequence for the actions editor or test cases. But I think it's not so important for now.

[wKich]

According to the call about what benefits could the storybook brings to design systems and testing components. We decided to focus on these aspects:

• Show component - interactor bindings. And how a user can interact with a component by showing the interactor's API. What components still don't have interactors. (Question. Maybe we could calculate how many interactions are covered by the interactor)
• Provide UI to execute interactor actions and investigate element props. Highlight bound element for that interactor and vice-versa.
• Give the possibility to write actions/tests directly in the addon for a separate component or a whole story. Save tests to the filesystem.
• Record user interaction and convert it to the action sequence
• Run tests directly in the user's browser or in the BigTest agents, show the result
• It's possible to built-in visual regression testing without the need to separate addon for that
• Check a11y for the component and during the execution of tests
• Show all Jest's tests (for a story or for the component). Allow to run them

For the first step, I'm going to integrate the interactor inspector to show the matched interactors for the current story, allow execute actions for these ones, show element's props, and highlight elements.