Merge pull request #23691 from dkurt:pycv_float16_fixes

Import and export np.float16 in Python #23691

### Pull Request Readiness Checklist

* Also, fixes `cv::norm` with `NORM_INF` and `CV_16F`

resolves https://github.com/opencv/opencv/issues/23687

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/src2/cv2_convert.cpp

@@ -88,6 +88,7 @@ bool pyopencv_to(PyObject* o, Mat& m, const ArgInfo& info)
                typenum == NPY_SHORT ? CV_16S :
                typenum == NPY_INT ? CV_32S :
                typenum == NPY_INT32 ? CV_32S :
+               typenum == NPY_HALF ? CV_16F :
                typenum == NPY_FLOAT ? CV_32F :
                typenum == NPY_DOUBLE ? CV_64F : -1;