Merge pull request #28968 from Prasadayus:Identity_function_fix_for_0D

Fixes the issue for Identity functions for 0D #28968

Closes https://github.com/opencv/opencv/issues/25763

### 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
- [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_util.hpp

@@ -14,6 +14,9 @@ void emit_failmsg(PyObject * exc, const char *msg);
 int failmsg(const char *fmt, ...);
 PyObject* failmsgp(const char *fmt, ...);
 
+int cvDepthToNumpyType(int depth);
+int numpyTypeToCvDepth(int typenum);
+
 //======================================================================================================================
 
 class PyAllowThreads