Add an example showing how to hide parts of field lines behind the solar disk

[Cadair]

Provide a general description of the issue or problem.

This came up in the chat: https://matrix.to/#/%21MeRdFpEonLoCwhoHeT%3Amatrix.org/%2417866230596068HWAmP%3Amatrix.org?via=matrix.org&via=openastronomy.org&via=cadair.com

But, I imagine could be quite useful especially when plotting from various points of view.