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/core/test/test_misc.cpp

@@ -8,10 +8,8 @@
 
 #include <opencv2/core/utils/fp_control_utils.hpp>
 
-#ifdef CV_CXX11
 #include <chrono>
 #include <thread>
-#endif
 
 namespace opencv_test { namespace {
 
@@ -282,9 +280,7 @@ public:
             // FP state is not supported
             // no checks
         }
-#ifdef CV_CXX11
         std::this_thread::sleep_for(std::chrono::milliseconds(100));
-#endif
     }
 
     cv::details::FPDenormalsModeState base_state;