Allow configure the UP direction for LookAt driver

[wentao]

The current implementation in

pub fn look_at<H: Handedness, V, Q>(forward: V) -> Q
where
    V: Into<mint::Vector3<f32>>,
    Q: From<mint::Quaternion<f32>>,
{
    let forward: Vec3 = forward.into().into();

    let result = forward
        .try_normalize()
        .and_then(|forward| {
            let right =
                H::right_from_up_and_forward::<Vec3, Vec3>(Vec3::Z, forward).try_normalize()?;
            let up = H::up_from_right_and_forward(right, forward);
            Some(Quat::from_mat3(&Mat3::from_cols(
                right,
                up,
                forward * H::FORWARD_Z_SIGN,
            )))
        })
        .unwrap_or_default();

    From::from(result.into())
}

hard code Vec3::Y as the look at up direction. It would be great to have that configurable, so this package can be used in different camera setup.