Foundation Classes, NCollection - Modernize code, add noexcept/constexpr (#793)

Foundation Classes, NCollection - Modernize code, add noexcept/constexpr (#793)

- Mark many methods and operators noexcept (iterators, containers, allocators, maps, lists, buffers, UTF/string utilities, etc.)
- Add constexpr to suitable functions and factory methods (matrices, vectors, static sizes) to enable compile-time usage
- Replace non-constexpr memcpy usages in NCollection_Mat3/NCollection_Mat4 with constexpr-friendly initialization and promote static arrays to constexpr
- Make several small API improvements: stronger const-correctness, noexcept on allocation/deallocation operators, delete forbidden copy ctors/assign where appropriate
- Remove obsolete NCollection_TypeDef.hxx and update FILES.cmake
- Miscellaneous small refactors to support modern C++ patterns and better compile-time guarantees