Switch CSS management for [Vartheme Admin] from LESS to SCSS with Gulp as the task manager

Thank you Jörg for reporting and the patch
Learning from your way.

After the review, we went with the sample change for now.
We will incorporate the full set of gulp and packages in the next optimization round for all Varbase components.

Jörg, Thanks for helping again
Learning to make it in the Drupal standard coding way as follows

I'm looking for a medium line but not complex way, so that joiner developers could start with

CSScomb settings for Drupal (CSS formatting and sort tool)

https://www.drupal.org/docs/develop/standards/css/csscomb-settings-for-d...

We may end-up adding number of gulp-sass tools which you used in your patch, in all Varbase components
Researching our options