Merge pull request #25075 from mshabunin:cleanup-imgproc-1

C-API cleanup: apps, imgproc_c and some constants #25075

Merge with https://github.com/opencv/opencv_contrib/pull/3642

* Removed obsolete apps - traincascade and createsamples (please use older OpenCV versions if you need them). These apps relied heavily on C-API
* removed all mentions of imgproc C-API headers (imgproc_c.h, types_c.h) - they were empty, included core C-API headers
* replaced usage of several C constants with C++ ones (error codes, norm modes, RNG modes, PCA modes, ...) - most part of this PR (split into two parts - all modules and calib+3d - for easier backporting)
* removed imgproc C-API headers (as separate commit, so that other changes could be backported to 4.x)

Most of these changes can be backported to 4.x.

modules/core/test/test_dxt.cpp

@@ -2,6 +2,7 @@
 // It is subject to the license terms in the LICENSE file found in the top-level directory
 // of this distribution and at http://opencv.org/license.html.
 #include "test_precomp.hpp"
+#include "opencv2/core/core_c.h"
 
 namespace opencv_test { namespace {
 
@@ -97,7 +98,7 @@ static void DFT_1D( const Mat& _src, Mat& _dst, int flags, const Mat& _wave=Mat(
         }
     }
     else
-        CV_Error(CV_StsUnsupportedFormat, "");
+        CV_Error(cv::Error::StsUnsupportedFormat, "");
 }
 
 
@@ -878,7 +879,7 @@ protected:
             {
                 cout << "actual:\n" << dst << endl << endl;
                 cout << "reference:\n" << dstz << endl << endl;
-                CV_Error(CV_StsError, "");
+                CV_Error(cv::Error::StsError, "");
             }
         }
     }