Core: De-duplicate babel use in core

[ndelangen]

What I did

I investigated the bundle meta file from esbuild for the core, and I noticed this:

Notice the exact same blocks 3 times in 3 entrypoints?
That's babel getting embedded 3 times.

Another way to look at it:

And I wondered, if this duplication can be dealt with by making an entry-point that exposes all these babel/transform related types and functions.

And the results are pretty good:

before:

after:

before:

after:

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

Before this change prettier would always be used to format files when we storybook them.
(save from controls, modifying main.ts etc.)

Now that only happens if we can find prettier as a dep.
(it's an optional peerDependency of the core)

No further testing instruction here, because there should be no user impact.

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>

name	before	after	diff	z	%
createSize	0 B	0 B	0 B	-	-
generateSize	76.4 MB	76.4 MB	0 B	0.99	0%
initSize	169 MB	150 MB	-18.9 MB	-227.17	🔰-12.6%
diffSize	92.8 MB	73.9 MB	-18.9 MB	-1629.27	🔰-25.6%
buildSize	7.46 MB	7.46 MB	267 B	2.21	0%
buildSbAddonsSize	1.62 MB	1.62 MB	0 B	1.14	0%
buildSbCommonSize	195 kB	195 kB	0 B	-	0%
buildSbManagerSize	2.3 MB	2.3 MB	0 B	-	0%
buildSbPreviewSize	352 kB	352 kB	0 B	1.36	0%
buildStaticSize	0 B	0 B	0 B	-	-
buildPrebuildSize	4.46 MB	4.46 MB	0 B	1.23	0%
buildPreviewSize	3 MB	3 MB	267 B	2.78	0%
testBuildSize	0 B	0 B	0 B	-	-
testBuildSbAddonsSize	0 B	0 B	0 B	-	-
testBuildSbCommonSize	0 B	0 B	0 B	-	-
testBuildSbManagerSize	0 B	0 B	0 B	-	-
testBuildSbPreviewSize	0 B	0 B	0 B	-	-
testBuildStaticSize	0 B	0 B	0 B	-	-
testBuildPrebuildSize	0 B	0 B	0 B	-	-
testBuildPreviewSize	0 B	0 B	0 B	-	-

name	before	after	diff	z	%
createTime	6.7s	21.1s	14.4s	0.58	68.2%
generateTime	19s	21.6s	2.6s	0.17	12%
initTime	15.7s	16s	304ms	-1.04	1.9%
buildTime	11.9s	11.6s	-290ms	-1	-2.5%
testBuildTime	0ms	0ms	0ms	-	-
devPreviewResponsive	7.8s	7.1s	-777ms	-0.48	-10.9%
devManagerResponsive	4.7s	4.5s	-124ms	-0.69	-2.7%
devManagerHeaderVisible	735ms	844ms	109ms	0.43	12.9%
devManagerIndexVisible	767ms	885ms	118ms	0.43	13.3%
devStoryVisibleUncached	1.3s	1.1s	-240ms	-1.05	-21.5%
devStoryVisible	766ms	884ms	118ms	0.39	13.3%
devAutodocsVisible	732ms	655ms	-77ms	-0.96	-11.8%
devMDXVisible	630ms	714ms	84ms	-0.08	11.8%
buildManagerHeaderVisible	678ms	681ms	3ms	-0.96	0.4%
buildManagerIndexVisible	683ms	681ms	-2ms	-1.02	-0.3%
buildStoryVisible	717ms	758ms	41ms	-0.62	5.4%
buildAutodocsVisible	690ms	617ms	-73ms	-1.45	🔰-11.8%
buildMDXVisible	631ms	614ms	-17ms	-1.04	-2.8%

Greptile Summary

This PR introduces changes to de-duplicate Babel usage in the Storybook core, aiming to reduce bundle size and improve performance.

• Added new 'babel' export in @storybook/core package.json
• Created centralized Babel entry point in 'code/core/src/babel/index.ts'
• Updated imports across multiple files to use '@storybook/core/babel'
• Added bundle analysis report generation in 'code/core/scripts/prep.ts'
• Introduced new Babel-related exports in CLI package for internal use

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[ndelangen]

How do you think this PR compares to yours here: #28571
@kasperpeulen ?

[shilman]

Amazing work @ndelangen -- this is a truly stupendous improvement!!!!!! ❤️ ❤️ ❤️

Approving on conditions that:

1. You've tested the metafile generation changes
2. You've tested the prettier changes
3. You document how to test in the PR description

Also, in the future it would be better to split the babel & prettier changes into two separate PRs. But I'm fine with the one PR since it's already prepared.