Implement curves that are restricted to a surface, for use in coil optimization

[dpanici]

https://github.com/hiddenSymmetries/simsopt/pull/289

We can take inspiration from @joaopedrobiu6 's work and implement curve winding surface-like objects in DESC, which would allow optimization of coils restricted to a winding surface, which would be useful when the winding surface is known a-priori.

For refernce, COILOPT did this first (Strickler 2002)