Exports a group of Drawing elements as an SVG document. In the exported file, the group is positioned at
[0, 0]. Its dimensions will be used as the default dimensions of the image. The export operation is asynchronous and returns a promise. The promise will be resolved with an SVG document encoded as a Data URI.
The root group containing all elements to export.
The export options.
Promise<string> - A promise that will be resolved with an SVG document encoded as a Data URI.