NextJS: Fix Image Context re-use via singleton

[martinnabhan]

What I did

#23881 was supposed to fix Image Context reuse, but it turns out that code/frameworks/nextjs/src/preview.tsx uses the CommonJS export (code/frameworks/nextjs/dist/image-context.js), while code/frameworks/nextjs/src/images/next-image.tsx etc. uses the ESM export (code/frameworks/nextjs/dist/image-context.mjs), causing the Image Context to not be reused and thus parameters specified in parameters.nextjs.image and applied in preview.tsx won't be available in next-image.tsx.

This pull request forces the use of the CommonJS export, even when using import, making sure the same Image Context is reused for both ESM and CommonJS imports.

Checklist for Contributors

Testing

The changes in this PR are covered in the following automated tests:

• stories
• unit tests
• integration tests
• end-to-end tests

Manual testing

If you check the Eager story from the previous pull request you can see the image isn't being eagerly loaded, while the Eager story of this branch properly eager loads the image.

Documentation

• Add or update documentation reflecting your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Checklist for Maintainers

• When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli/src/sandbox-templates.ts

• Make sure this PR contains one of the labels below:

  Available labels

  • bug: Internal changes that fixes incorrect behavior.
  • maintenance: User-facing maintenance tasks.
  • dependencies: Upgrading (sometimes downgrading) dependencies.
  • build: Internal-facing build tooling & test updates. Will not show up in release changelog.
  • cleanup: Minor cleanup style change. Will not show up in release changelog.
  • documentation: Documentation only changes. Will not show up in release changelog.
  • feature request: Introducing a new feature.
  • BREAKING CHANGE: Changes that break compatibility in some way with current major version.
  • other: Changes that don't fit in the above categories.

🦋 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>

[martinnabhan]

@ndelangen Sorry to bother you with this again. Could you please take a look?

[yannbf]

Hey @ndelangen would you mind checking this out whenever you have time? Thanks!

It might take some time as we are quite busy, we really appreciate your efforts and patience <3