Avoid duplication of coefficients of sonic's CS

[osuketh]

Avoid duplication of code. coefficients vector coeffs can be reused to polynomial commitment.

zero-chain/core/sonic/src/helped/prover.rs

Lines 71 to 75 in fc58913

	blindings.iter().rev() // ascending order variables
	.chain_ext(wires.c.iter().rev())
	.chain_ext(wires.b.iter().rev())
	.chain_ext(Some(E::Fr::zero()).iter()) // power i is not equal zero
	.chain_ext(wires.a.iter()),

zero-chain/core/sonic/src/helped/prover.rs

Lines 96 to 101 in fc58913

	let mut rx1 = wires.b; // X^{-n}...X^{-1}
	rx1.extend(wires.c); // X^{-2n}...X^{-n-1}
	rx1.extend(blindings.clone()); // X^{-2n-4}...X^{-2n-1}
	rx1.reverse();
	rx1.push(E::Fr::zero());
	rx1.extend(wires.a); // X^{1}...X^{n}