request support for sass-embedded

[mastermatt]

Description

The folks behind Dart Sass recently released the 1.x of sass-embedded, which has the same API as their sass lib except it wraps the Dart executable instead of being a pure JS option. This makes it much faster, but limits the systems it can run on.

Describe the solution you'd like

Unfortunately, sass is prohibitively slow for the the project I'm working on is. It would be great if this lib supported both sass and sass-embedded as optional peer dependencies.

Describe alternatives you've considered

Currently, I'm stuck using styled-jsx-plugin-sass and node-sass.