Polylines normal to the earth's surface disappear in 2D

It's pretty simple, if a line is normal to the earth, it disappears in 2D. Ideally, we would use the width and outline of the line to turn it into a point in 2D mode. We have some code in DynamicScene that creates points on the fly using billboards, we might be able to adapt/refactor that out for this use case as well. I have an example CZML that shows the issue if anyone wants to look at this.

Start by reproducing the issue with the example CZML and inspect DynamicScene's billboard-based point creation. Determine how a polyline normal to the earth's surface is handled in 2D mode; done means its width and outline still produce a visible point-like rendering.

Written by the indexing model from the issue text.