Add Extra Interpolation and Spline Methods for Funding curves

[domokane]

Would like to add additional methods from Hagan West.

Forward Monotone Convex Spline Raw Interpolation Minimalist Quadratic Interpolator

An implementation can be found here.

https://github.com/KNFO-MIMUW/Hagan_West_interpolation

[quantinsights]

Hi @domokane, I would also be interested to work on this task.

[domokane]

OK. I already added some but it's fine to add more. Let me know before you begin. Thanks D