Replace node-sass with sass

[juanolalla]

node-sass is deprecated, and according to it's page, projects that still use it should move onto Dart Sass (sass). This can lead to different problems, like on my local I couldn't use node-sass because "Node Sass does not yet support your current environment: OS X 64-bit...".

On Gruntfile.coffee we would need to replace const sass = require('node-sass') with const sass = require('sass').

[neclimdul]

Similarly, node-sass uses the obsolete gyp build framework which requires python2 which is also obsolete and no longer on modern linux distro's like ubuntu 23.04.

I had to setup some containers with old versions of node/python/etc to get a build together to help contribute.