We're at a point where we have relative freedom to change the `getSVG` function signature, since it hasn't really been "released" yet. My gut says it should match the getPixmap signature (that is `documentId, layerId, options`) and `options` should be an object that will currently only have one option: `scale`).

@isonno Is that okay with you? If so, I'm willing to make the appropriate change in generator-assets at the same time and make sure everything gets into perforce.