Merge pull request #27246 from gursimarsingh:bug_fix/mcc_dnn_dependency

Fix hard dependency of dnn for mcc module. #27246

Currently building objdetect module without dnn fails due to mcc module. This PR makes the dependency optional, by checking if DNN is available in mcc module. 

### 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

modules/objdetect/misc/python/pyopencv_cchecker.hpp

@@ -1,4 +0,0 @@
-#include "opencv2/objdetect/mcc_checker_detector.hpp"
-
-typedef std::vector<cv::Ptr<mcc::CChecker>> vector_Ptr_CChecker;
-typedef dnn::Net dnn_Net;

modules/objdetect/misc/python/pyopencv_objdetect.hpp

@@ -3,5 +3,9 @@
 #include "opencv2/objdetect.hpp"
 
 typedef QRCodeEncoder::Params QRCodeEncoder_Params;
+typedef std::vector<cv::Ptr<mcc::CChecker>> vector_Ptr_CChecker;
+#ifdef HAVE_OPENCV_DNN
+typedef dnn::Net dnn_Net;
+#endif
 
 #endif