Adding SegmentedContour

Adding a utility class for TessRenderPath to turn a RawPath into a segmented contour that it can then triangulate. More of the "move towards composition vs inheritance" work. Also removes old ContourRenderPath as this effectively replaces the logic it tried to implement via inheritance.

This mostly moves that old code around, in doing so it also adopts the new path iteration which leaves the "quad" case for the segmenter unhandled, which is ok for now as none of our render paths currently have quad commands.

Diffs=
98647c98c Change based on feedback
1db72a148 Adding SegmentedContour and removing old contour_render_path

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