How to include a non-plugin based feature of CKEditor (TextTransformation)?

[lukew-cogapp]

Description

CKEditor features Text Transformation functionality:
https://ckeditor.com/docs/ckeditor5/43.3.1/features/text-transformation.html
However, this is part of the ckeditor5 package and installation instructions include:
import { ClassicEditor, TextTransformation } from 'ckeditor5';

We don't believe this is a "first party plugin", as it is not listed separately. here:
https://github.com/ckeditor/ckeditor5/tree/master/packages

Therefore, we're not sure what the best way to go about including this functionality is.

We tried this, but the TextTransformation plugin cannot be found:

{
    "plugins": [ "TextTransformation" ],
    "textTransformation": {
        "extraTransformations": {
            "quotes": true,
            "dashes": true
        }
    }
}

How might we go about this?
Thanks,
Luke