Allow use of `sass` executable found in PATH for offline usage

[akram]

It could be useful for offline mode and air-gapped developers to allow the plugin to use the sass executable to be found in PATH instead of downloading or maintaining a <cachedFilesDirectory>

Could this be implement with an additional parameter or as a default failsafe behaviour?

[cleydyr]

Hey, Akram. Certainly, we could add a new parameter in future versions. The idea of trying to fall back to searching the path for the sass executable sounds interesting to me as well.

I'd welcome a PR implementing the suggestions. :)