BREAKING CHANGE
Since `next export` has been printing a deprecation warning since https://github.com/vercel/next.js/pull/47376, its safe to remove in semver-major.
The upgrade path is to simply add `output: 'export'` in `next.config.js` - everything will continue to work the same.
This config greatly improves the `next dev` experience today. And in the future, it will improve performance of `next build` because we no longer need to do two passes (build then export).
Skips additional production-only tests.
Follow-up to #56089.
In this PR I went through all of `test/integration` looking for `nextBuild(` and added the skipping logic.
This PR adds a new configure property, `images.loaderFile` that allow
you to define a path to a file with an exported image loader function.
This is useful when migrating from `next/legacy/image` to `next/image`
because it lets you configure the loader for every instance of
`next/image` once, similar to the legacy "built-in loaders".