Add the ability to reconstruct stellarator plasma boundary in CAD form

[ym1906]

As a modeller and reactor designer I want to develop the capability to optimise stellarator designs with Bluemira. This requires the ability to represent the plasma's boundary in CAD form.

The software package Simsopt is widely used to optimise stellarators. Simsopt can generate a 3D plasma surface but this must be translated into a NURBS (Non-uniform rational B Spline) surface for CAD representation within Bluemira.

Edit: Add in the ability to plot stellarator magnets too.

Proposed solution

There are two parts to the solution:

1. Convert the plasma surface to control points, knots, and multiplicities read into Bluemira.
2. Add the functionality to Bluemira for generating NURBS surfaces from the above data.