Fork arkworks in order to add non-pairing friendly curves

[Mikerah]

Currently, we are using arkworks as the basis for the elliptic curves and other finite field arithmetic (see #19). However, it is missing a few key curves that will be relevant for the initial projects we have planned for StoffelMPC, namely secp256k1. We will need to fork the algebra and curve arkworks libraries and add these curves as needed. Then, it can be pushed and merged upstream according to arkworks maintenance team.