Core: Deprecate storyStoreV6 (including storiesOf) and storyIndexers

[JReinhold]

Works on #23457

What I did

• Added deprecation warning for storyIndexers and for the corresponding types
• Added migration notes for storyIndexers
• Added deprecation warning and migration notes for storyStoreV6, explicitly calling out storiesOf

The deprecation warning for storyIndexers only appears when a deprecated indexer is handling a file, not just when it's configured. That way, addon authors can support both the old and new API by setting both properties and not get punished with a deprecation warning. In SB 7.5.0 storyIndexers will simply be ignored, while previous versions will ignore experimental_indexers.

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

I tested this by adding features: { storyStoreV7: false } to the configuration and saw the deprecation warning in both dev and build. The warnings are not shown if it's true nor if it's unspecified.

I tested the storyIndexers deprecation warning by adding an indexer to the config and removing all experimental_indexers with:

// .storybook/main.ts

import { readFileSync } from 'fs';
import { loadCsf } from '@storybook/csf-tools';

export default {
  experimental_indexers: () => [],
  storyIndexers = (indexers) => [
    {
      test: /(stories|story)\.[tj]sx?$/,
      indexer: async (fileName, options) => (await readCsf(fileName, options)).parse(),
    },
    ...(indexers || []),
  ],
};

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>

[tmeasday]

LGTM! Great stuff

[ndelangen]

@yannbf I'd like to hear your opinion on if we should continue to do deprecations warnings like this -in place-?

I'd love to figure out a way to use the errors-consolidation work you've done, to consolidate deprecation warnings like these.

[yannbf]

let's create a task for this!