[HyperNova] Rework the API to be NIMFS-centric

[CPerezz]

This can be 1/N tasks about API improvement. In particular, the idea is to fix the foundations of the library to a Nimfs object which will contain:

• The MLE(CCS.M) (and we'll see if the CCS.Matrixes are even needed).
• An LCCCS instance which references the MLE's of the parent object that holds it.
• A set of functions that allows the NIMFS to perform the folding as well as to prepare new inputs for the folding process.

Aside from that, the idea is to get ridd of the Shape, Instance, and witness objects and istead work with arrays directly or, even, SparsePolynomial/SparseVec primitives as suggested in #21.

There's also a bunch of API suggestions in the current hypernova branch marked with XXX across the repo.

[CPerezz]

Closed via #41