Polynomials are evaluated twice (before multiopen and inside multiopen)

[kunxian-xia]

The ProverQuery struct does not contain the evaluation of the poly at the point (which is already computed before we invoke the multiopen prover).

halo2/halo2_proofs/src/poly/query.rs

Lines 20 to 29 in b8e458e

	/// A polynomial query at a point
	#[derive(Debug, Clone)]
	pub struct ProverQuery<'com, C: CurveAffine> {
	/// point at which polynomial is queried
	pub(crate) point: C::Scalar,
	/// coefficients of polynomial
	pub(crate) poly: &'com Polynomial<C::Scalar, Coeff>,
	/// blinding factor of polynomial
	pub(crate) blind: Blind<C::Scalar>,
	}

Then the multiopen prover will evaluate the polynomials again. Therefore, I suggest we add another field called eval of type C::Scalar in the ProverQuery struct.