Transform Sass asset file extensions in block.json

[cr0ybot]

Related Issue/RFC: #419

Description of the Change

When a Sass file is used as a custom block asset, and the asset is set to a .css file in block.json, an error is thrown related to automatic version string generation because a file with that name and extension are not available in the source folder.

This PR duplicates the existing functionality that transforms TypeScript asset extensions in block.json for Sass files (.sass/.scss => .css).

block.json input:

{
  "style": "file:./style.scss"
}

block.json output:

{
  "style": "file:./style.css"
}

Alternate Designs

I could have changed the way that the version string generator works, but that is much less straightforward than just providing the file that the existing code is looking for (while also following the existing example set by the treatment of TypeScript files).

Possible Drawbacks

I realize that 10up seems to be moving away from Sass, but the workflow still inherently supports it.

A possible, but tiny, drawback is that this will likely change the generated version string in existing projects.

Verification Process

I verified the fix by running npm start in an existing project where I discovered the original issue. I also added and ran the tests successfully.

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests passed.
• I have added a changeset to my PR. See CONTRIBUTING document for instructions

[changeset-bot]

🦋 Changeset detected

Latest commit: 6573d42

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
10up-toolkit	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[cr0ybot]

Let me know if this should include a change to the documentation. I didn't see anything about block.json and TypeScript specifically in the docs so I didn't include anything, but it could be warranted.

[fabiankaegy]

Thanks so much for working on this. Nice job on the tests also!

I also ran a few tests on my end and it all works as expected :)

Merging this now and will see if we can get a release out the door early in the new year 👍