Make Prover generic over the ConstraintCommitment type

[gswirski]

For better GPU performance, allow provers to customize ConstraintCommitment implementation/memory layout.

Implementors of the Prover trait would need to add the following lines since default associated types are unstable.

    type ConstraintCommitment<E: FieldElement<BaseField = Felt>> = DefaultConstraintCommitment<E, H, Self::VC>;

   [...]

    #[maybe_async]
    fn build_constraint_commitment<E: FieldElement<BaseField = Felt>>(
        &self,
        composition_poly_trace: CompositionPolyTrace<E>,
        num_constraint_composition_columns: usize,
        domain: &StarkDomain<Self::BaseField>,
        partition_options: PartitionOptions,
    ) -> (Self::ConstraintCommitment<E>, CompositionPoly<E>) {
        DefaultConstraintCommitment::new(composition_poly_trace, num_constraint_composition_columns, domain, partition_options)
    }

[irakliyk]

Looks great! Thank you! I left a couple of small comments inline. Also, we should update the main README file (as it contains an example of how to instantiate a prover (i.e., WorkProver)) and the prover crate README file.

[irakliyk]

All looks good! Thank you!