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/objdetect/test/test_qrcode_encode.cpp

@@ -5,16 +5,6 @@
 #include "test_precomp.hpp"
 namespace opencv_test { namespace {
 
-#if !defined CV_CXX11
-// Wrapper for generating seeded random number via std::rand.
-template<unsigned Seed>
-class SeededRandFunctor {
-public:
-    SeededRandFunctor() { std::srand(Seed); }
-    int operator()(int i) { return std::rand() % (i + 1); }
-};
-#endif
-
 std::string encode_qrcode_images_name[] = {
         "version1_mode1.png", "version1_mode2.png", "version1_mode4.png",
         "version2_mode1.png", "version2_mode2.png", "version2_mode4.png",