feat(SASS): Allow import scss files from lib or dependencies

[rtrompier]

This feature allow the developer to import other SCSS files into the scss component file.

Eg :
From node_modules dependencies : @import '~angular/material/theming';
From other component : @import '../other-component/other-component.component.scss';

[paesku]

I tested this locally and it works like a charme.
IMO this request should be accepted, since it's such an important part when building libraries and sharing settings, functions and mixins via scss files.

[jvandemo]

@rtrompier — Thank you, this works great! 👍

Would you be able to add a section to the README so I can merge this?

Thanks in advance!

[jvandemo]

@rtrompier — I have added the documentation and released your changes as v10.2.0.

Thank you for your contribution! 👍

[sgentile]

Question: @rtrompier - where inside the generator code would I put a global .scss file in which to import my styles - I have several components and want to have it used for them all