Merge pull request #28887 from milllemonman:4.x

hal/riscv-rvv: implement laplacian #28887

OpenCV Extra: https://github.com/opencv/opencv_extra/pull/1353

An implementation of laplacian for riscv-rvv hal

Added benchmark in perf_laplacian.cpp
The performance is evaluated on K1 by running 
./opencv_perf_imgproc --gtest_filter="Perf_Laplacian*"
Results are attached in the figure below.

CV_8U fast path supports ksize=3 with BORDER_CONSTANT/BORDER_REPLICATE; unsupported combinations fall back to default implementation. See performance results bellow.

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [ ] There is a reference to the original bug report and related work
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake

hal/riscv-rvv/include/imgproc.hpp

@@ -241,6 +241,16 @@ int integral(int depth, int sdepth, int sqdepth,
 //#undef cv_hal_integral
 //#define cv_hal_integral cv::rvv_hal::imgproc::integral
 
+/* ############ laplacian ############ */
+int laplacian(const uint8_t* src_data, size_t src_step,
+              uint8_t* dst_data, size_t dst_step,
+              int width, int height,
+              int src_depth, int dst_depth, int cn,
+              int ksize, int border_type, uint8_t border_value);
+
+#undef cv_hal_laplacian
+#define cv_hal_laplacian cv::rvv_hal::imgproc::laplacian
+
 /* ############ scharr ############ */
 int scharr(const uint8_t *src_data, size_t src_step, uint8_t *dst_data, size_t dst_step, int width, int height, int src_depth, int dst_depth, int cn, int margin_left, int margin_top, int margin_right, int margin_bottom, int dx, int dy, double scale, double delta, int border_type);