NextJS: Turn withStorybook into ergonomic module export

[shilman]

This is a little cleaner in your next.config.js and matches what other NextJS plugins are doing

Testing

Update your next.config.js to:

const withStorybook = require('@storybook/nextjs-server/next-config')();
module.exports = withStorybook({ /* existing nextjs config */ });

🦋 Canary release

This PR does not have a canary release associated. You can request a canary release of this pull request by mentioning the @storybookjs/core team here.

core team members can create a canary release here or locally with gh workflow run --repo storybookjs/storybook canary-release-pr.yml --field pr=<PR_NUMBER>

[tmeasday]

Sure. Do we need to make the cts change? Wasn't it working before? No stress either way

[shilman]

@tmeasday No, when it's .ts you need to do this AFAICT, which sucks. There might be a better way around it, but .cts works cc @valentinpalkovic

const withStorybook = require('...').default();