Merge pull request #27581 from dkurt:d.kuryaev/dlpack

### Pull Request Readiness Checklist

resolves #16295

```
docker run --gpus 0 -v ~/opencv:/opencv -v ~/opencv_contrib:/opencv_contrib -it nvidia/cuda:12.8.1-cudnn-devel-ubuntu22.04
apt-get update && apt-get install -y cmake python3-dev python3-pip python3-venv &&
python3 -m venv .venv &&
source .venv/bin/activate &&
pip install -U pip &&
pip install -U numpy &&
pip install torch --index-url https://download.pytorch.org/whl/cu128 &&
cmake \
    -DWITH_OPENCL=OFF \
    -DCMAKE_BUILD_TYPE=Release \
    -DBUILD_DOCS=OFF \
    -DWITH_CUDA=ON \
    -DOPENCV_DNN_CUDA=ON \
    -DOPENCV_EXTRA_MODULES_PATH=/opencv_contrib/modules \
    -DBUILD_LIST=ts,cudev,python3 \
    -S /opencv -B /opencv_build &&
cmake --build /opencv_build -j16
export PYTHONPATH=/opencv_build/lib/python3/:$PYTHONPATH
```

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
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake

modules/python/test/test_cuda.py

@@ -145,5 +145,18 @@ class cuda_test(NewOpenCVTests):
         self.assertEqual(True, hasattr(cv.cuda, 'fastNlMeansDenoisingColored'))
         self.assertEqual(True, hasattr(cv.cuda, 'nonLocalMeans'))
 
+    def test_dlpack_GpuMat(self):
+        for dtype in [np.int8, np.uint8, np.int16, np.uint16, np.float16, np.int32, np.float32, np.float64]:
+            for channels in [2, 3, 5]:
+                ref = (np.random.random((64, 128, channels)) * 255).astype(dtype)
+                src = cv.cuda_GpuMat()
+                src.upload(ref)
+                dst = cv.cuda_GpuMat.from_dlpack(src)
+                test = dst.download()
+                equal = np.array_equal(ref, test)
+                if not equal:
+                    print(f"Failed test with dtype {dtype} and {channels} channels")
+                self.assertTrue(equal)
+
 if __name__ == '__main__':
     NewOpenCVTests.bootstrap()