algorithms/div/knuth: Delegate to div_nxm_normalized if normalized.

[github-actions]

On 2022-10-24 @recmo wrote in fb3aa20 “Merge pull request #172 from recmo/div2”:

Delegate to div_nxm_normalized if normalized.

    let n = divisor.len();
    let m = numerator.len() - n;

    // Compute normalized divisor double-word and reciprocal.
    // TODO: Delegate to div_nxm_normalized if normalized.
    let (d, shift) = {
        let d = u128::join(divisor[n - 1], divisor[n - 2]);
        let shift = d.high().leading_zeros();
        (
            if shift == 0 {

From src/algorithms/div/knuth.rs:96