Draft: Add a way to set the polygon length from the star-toolbar

Abandoned

This MR is a record of a small bit of work which didn't end up working out. It is available for anyone who wants to complete it.

Abstract

For controlling polygons/stars, we want to be able to show how big each side of the polygon is as well as allow the user to control the star or polygon from it's side-length.

Test File: polygons.svg

Problems

1. Transformation into correct units is wrong, not sure why. could be the calculation of the diameter, might be the transformation applied.
2. When applying the transformation the center point is incorrect resulting in an added translation