polynomial coefficients recovery

[dariolina]

Similar to normal erasure coding recovery, but recovers the polynomial in coefficient form for use with KZG, instead of source chunks. Corresponds to recover_poly_from_samples from rust_kzg but without the last FFT in this line (as proposed in this upstream issue). See spec.

fn recover_poly(
            samples: &[Option<BlsScalar>],
            fs: &FFTSettings,
        ) -> Result<Polynomial, Error> {
       }

[nazar-pc]

From experimental testing, the cost of this is quite low for us, so not a priority for now