Extract SVGs directly from Sketch file

Instead of having to manually export and commit the icons to this repo, consider having a SSOT: the original Sketch file.

I've found this project but not sure if it helps: https://github.com/souporserious/sketch-to-svg-json-loader

Nonetheless, the Sketch file format is pretty open so it should be possible to export the layers to SVGs.

There's also this Node library: https://www.npmjs.com/package/node-sketch

/cc @timzallmann