Switch from deprecated Node Sass to Dart Sass compiler using Gulp and change minimum node version to 16.0 and later in the Varbase Style Guide module

Problem/Motivation

Following with latest changes from Drupal core package.json file

Warning: LibSass and Node Sass are deprecated. While they will continue to receive maintenance releases indefinitely, there are no plans to add additional features or compatibility with any new CSS or Sass features. Projects that still use it should move onto Dart Sass.
https://www.npmjs.com/package/node-sass

• The maintainers no longer recommend LibSass for new Sass projects. Use Dart Sass instead.
• The maintainers recommend all existing LibSass users make plans to eventually move onto Dart Sass, and that all Sass libraries make plans to eventually drop support for LibSass.
• The maintainers are no longer planning to add any new features to LibSass, including compatibility with new CSS features.
• LibSass and Node Sass will continue to be maintained indefinitely on a best-effort basis, including fixing major bugs and security issues and maintaining compatibility with the latest Node versions.

Proposed resolution

• Switch from Node Sass to Dart Sass compiler
• Using Gulp with Dart Sass

Change from sass = require("gulp-sass"), to sass = require("gulp-sass")(require('sass')), in the gulpfile.js file
Have the following changes in the package.json file and update the yarn.lock file

    ...
    ...
    "sass": "~1",
    "gulp": "~4",
    "gulp-autoprefixer": "~8",
    "gulp-clean-css": "~4",
    "gulp-concat": "~2",
    "gulp-csscomb": "~3",
    "gulp-filter": "~7",
    "gulp-html-replace": "~1",
    "gulp-postcss": "~8",
    "gulp-rename": "~2",
    "gulp-sass": "~5",
    "gulp-scss-lint": "~1",
    "gulp-sourcemaps": "~3",
    "gulp-uglify": "~3",
    ...
    ...

• Update the minimum node version to 16.0 and more
  

    "engines": {
      "yarn": ">= 1.6",
      "node": ">= 16.0"
    },
  

Remaining tasks

• ✅ File an issue about this project
• ✅ Addition/Change/Update/Fix to this project
• ✅ Testing to ensure no regression
• ➖ Automated unit/functional testing coverage
• ✅ Developer Documentation support on feature change/addition
  
  Added
  Switch From Node SASS to Dart SASS for old Sub-Themes
  Changed
  Update NPM and Nodejs to the ~16 LTS version
• ➖ User Guide Documentation support on feature change/addition
• ➖ Accessibility and Readability
• ✅ Code review from 1 Varbase core team member
• ✅ Full testing and approval
• ✅ Credit contributors
• ✅ Review with the product owner
• ✅ Update Release Notes and Update Helper on new feature change/addition
• ✅ Release varbase-9.0.6, varbase_styleguide-9.0.3

Varbase update type

• ✅ No Update
• ➖ Optional Update
• ➖ Forced Update
• ➖ Forced Update if Unchanged

User interface changes

• N/A

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• Issue #3272507: Switched from deprecated Node Sass to Dart Sass compiler using Gulpand change minimum node version to 16.0 and later in the Varbase Style Guide module
  
  Added
  Switch From Node SASS to Dart SASS for old Sub-Themes
  Changed
  Update NPM and Nodejs to the ~16 LTS version