blurAsync function
Blur blurs an image Mat using a normalized box filter.
For further details, please see: https:///docs.opencv.org/master/d4/d86/group__imgproc__filter.html#ga8c45db9afe636703801b0b2e440fce37
Implementation
Future<Mat> blurAsync(Mat src, (int, int) ksize, {Mat? dst}) async {
  dst ??= Mat.empty();
  return cvRunAsync0((callback) => cimgproc.cv_blur(src.ref, dst!.ref, ksize.cvd.ref, callback), (c) {
    return c.complete(dst);
  });
}