Implements the witness map used by snarkjs. The arkworks witness map calculates the
coefficients of H through computing (AB-C)/Z in the evaluation domain and going back to the
coefficients domain. snarkjs instead precomputes the Lagrange form of the powers of tau bases
in a domain twice as large and the witness map is computed as the odd coefficients of (AB-C)
in that domain. This serves as HZ when computing the C proof element.
Implements the witness map used by libsnark. The arkworks witness map calculates the
coefficients of H through computing (AB-C)/Z in the evaluation domain and going back to the
coefficients domain.