Add utility to create a FourierRZCurve out of a FourierRZToroidalSurface

[dpanici]

Add a util to make FourierRZCurve out of FourierRZToroidalSurface at a constant theta/zeta @rahulgaur104 (evaluate basis at constant theta, and then find the coefficients that describe it directly from the surface's basis)

[dpanici]

just using from_values would do the same thing already now @dpanici add the code

[dpanici]

Util function where you add theta(zeta) fxn so you don't have to do Grid