Merge pull request #23736 from seanm:c++11-simplifications

Removed all pre-C++11 code, workarounds, and branches #23736

This removes a bunch of pre-C++11 workrarounds that are no longer necessary as C++11 is now required.
It is a nice clean up and simplification.

* No longer unconditionally #include <array> in cvdef.h, include explicitly where needed
* Removed deprecated CV_NODISCARD, already unused in the codebase
* Removed some pre-C++11 workarounds, and simplified some backwards compat defines
* Removed CV_CXX_STD_ARRAY
* Removed CV_CXX_MOVE_SEMANTICS and CV_CXX_MOVE
* Removed all tests of CV_CXX11, now assume it's always true. This allowed removing a lot of dead code.
* Updated some documentation consequently.
* Removed all tests of CV_CXX11, now assume it's always true
* Fixed links.

---------

Co-authored-by: Maksim Shabunin <maksim.shabunin@gmail.com>
Co-authored-by: Alexander Smorkalov <alexander.smorkalov@xperience.ai>

modules/python/src2/cv2_util.cpp

@@ -128,11 +128,7 @@ void pyPopulateArgumentConversionErrors()
         PySafeObject exception_message(PyObject_Str(exception_value));
         std::string message;
         getUnicodeString(exception_message, message);
-#ifdef CV_CXX11
         conversionErrorsTLS.getRef().push_back(std::move(message));
-#else
-        conversionErrorsTLS.getRef().push_back(message);
-#endif
     }
 }