Feat/#174 generalize mul op

[KimiWu123]

closed item3 in #174

[hero78119]

👍 LGTM!!

reporting an edge case

#[test]
        fn test_mul64_16_w_overflow_test() {
            let wit_a = vec![0, 0, 0, u16::MAX as u64];
            let wit_b = vec![0, 0, 0, u16::MAX as u64];
            let wit_c = vec![0, 0, 0, 0];
            let wit_carries = vec![0, 0, 0];
            let witness_values = [wit_a, wit_b, wit_c, wit_carries].concat();
            verify::<64, 16, E>(witness_values, false);
        }

and plan to further investigate in #98