Image trace vectorization

One possibility of library is https://github.com/visioncortex/vtracer but there may be others worth researching and considering.

Start by researching the proposed visioncortex/vtracer library and other image-tracing options suitable for Graphite. The issue names no files, tests, or entry points, so first determine where image import and vectorization belong; done would require a decided implementation approach and defined integration scope.

Written by the indexing model from the issue text.