Packages: Move story-editor to new structure

[swissspidy]

Feature Description

💡 The goal here is to create two packages ⚠️

Package 1: story-editor

Proof-of-concept: https://github.com/google/web-stories-wp/tree/try/next-level-packages/packages/story-editor/src

This package will basically just export a ton of stuff.

-> Dashboard will import any dependencies from here for now (there will be way fewer once #8373 lands)
-> Web Stories block will import any dependencies from this package (until #8327 lands)

• Move code from /assets/src/edit-story to /packages/story-editor/src/
• Make packages/story-editor/index.js just export all components needed by others
• Update imports where necessary.
  Use @web-stories-wp/... imports for anything that is already a package, relative imports for everything else.
• Create /packages/story-editor/package.json referencing its dependencies
• Create /packages/story-editor/README.md with short documentation.

Package 2: wp-story-editor

Proof-of-concept: https://github.com/google/web-stories-wp/blob/f02da9e83a879b316e31b7d13bd62bd1dc8c9014/packages/wp-story-editor/src/index.js

• Move /assets/src/edit-story/index.js to /packages/wp-story-editor/src/index.js, updating all references to import from @web-stories-wp/story-editor
• Create /packages/wp-story-editor/package.json referencing its dependencies
• Create /packages/wp-story-editor/README.md with short documentation.

Do not alter or remove anything below. The following sections will be managed by moderators only.

Acceptance Criteria

Implementation Brief

For the remaining dependencies:

• packages/story-editor/karma/fixture can continue to import FixtureEvents from assets/src/karma-fixture for now
• The formattedTemplatesArray array used in story editor karma tests should be copied to packagers/story-editor/karma/fixture/db/templates.js and imported from there

Also:

• Ensure .storybook/stories/playground/index.js still imports & renders editor correctly.

[spacedmonkey]

Highlighting these places

https://github.com/google/web-stories-wp/blob/87fd694c9ede861ce56f4fcedbb0c8adf3ef6946/assets/src/edit-story/karma/fixture/fixture.js#L46

https://github.com/google/web-stories-wp/blob/2ba05276e15bb252b7c2d4d07c648d86029efd6c/assets/src/edit-story/components/library/panes/pageTemplates/karma/pageTemplatesPane.karma.js#L27

https://github.com/google/web-stories-wp/blob/876833e66997a45ac4916ad69cf1facb91538e87/assets/src/edit-story/components/canvas/displayLayer.js#L63

[swissspidy]

@spacedmonkey With #8388 in mind, I think we can proceed with moving the editor to its own package. Moving to "Ready for Sprint" for now

[mohdsayed]

With #8561 merged, shall we close this issue?