Upgrade webpack v4 to v5

[peterp]

Previously we were blocked by the fact that Storybook was on Webpack 4, but they've already upgraded to Webpack 5.

Here are the docs for upgrading: https://webpack.js.org/migrate/5/

[peterp]

It looks like Storybook does not support Webpack 5: storybookjs/storybook#13392 :/

[Tobbe]

We use chalk a lot. Would this be an issue for us as well? facebook/create-react-app#10198

[Tobbe]

Storybook Wp5 support:

[thedavidprice]

Now that we've upgraded to Storybook v6, which is using Webpack v5, when should we prioritize upgrading to Webpack v5 @peterp?

[dthyresson]

@jtoar Will an upgrade to Webpack v5 be needed if upgrading to PostCss 8? See: #2123