Main module headers are moved 1 level up

e.g. <opencv2/core/core.hpp> become <opencv2/core.hpp>

Also renamed <opencv2/core/opengl_interop.hpp> to <opencv2/core/opengl.hpp>

modules/java/generator/src/cpp/converters.h

@@ -1,5 +1,5 @@
 #include "opencv2/opencv_modules.hpp"
-#include "opencv2/core/core.hpp"
+#include "opencv2/core.hpp"
 #include "features2d_manual.hpp"
 
 void Mat_to_vector_int(cv::Mat& mat, std::vector<int>& v_int);