feat: Use fastdom to batch writes and avoid sync layout (take two)

[diagramatics]

Continuing from #385. Sorry for the hijack @STRML I was going to force push to the PR branch instead but I realised it's on a separate repo 😢

When animating a large number of elements, it can be helpful to batch these animations up into a single mutate operation using fastdom to improve forced synchronous layout stalls.

This PR fixes the enter animations by running the class mutation for enter on the event handler, skipping fastdom and only relying it on the -active class. The difference is on instead of recalculating the DOM by forcefully invalidating it on every animation, the recalculation happens at the end of the frame per the browser logic. This is huge for animations where more than one element is being animated at the same frame. Results are on the flamecharts below on the TransitionGroup story when set to animate 3 elements at once.

Before:

Notice the expensive style recalculation and relayouts on every animation done.

After:

PR also fixes the missing webpack-atoms dependency to run Storybook.

[STRML]

Good call on the immediate flag, just a lot of noise from webpack-atoms here

[STRML]

Intended? This should be a separate PR

[diagramatics]

Closing since #385 is updated now.