I think this feature is already there. In the palette (on the right of the window) select "Edge Types". If you hover with the mouse on the icons, it will show all the edge types: polyline (the default), arc, bezier, quadratic, spline.
You can either drag and drop the edge icon you want, or you can select an existing edge on the main canvas, then right-click on the edge icon that you want and select "Apply type" to transform the selected edge to the new type.