Add support for dart-sass

[nwpappas]

What problem does this feature solve?

Dart Sass is the primary implementation of Sass, which means it gets new features before any other implementation. It would allow for the greatest number of Sass functionality to be used in conjunction with Vue and Rollup.

The Sass project has an open issue on helping projects migrate:
sass/dart-sass#267

What does the proposed API look like?

The API should not change from a user point of view. The means of compiling Sass behind the scenes simply changes.

[znck]

It's an upstream change. vuejs/component-compiler-utils#56

keeping this issue open to track.

[gwardwell]

@znck It looks like this issue can be closed now, right? I can across it when trying to determine if rollup-plugin-vue supports dart-sass and the Sass module system. After a little confusion, I just tried a sass module in my project and it worked. So this isn't waiting or blocked anymore, right?

[znck]

Yes, dart-sass is already supported.

[funyapu]

Hi,

It seems@use statement not working in both SFC and auto import.
Is this matter of upstream?

Replacing @use with @import solves build failure, but do print css multiple times :(