MSVC C4996 C++17 deprecation warning

[jeremyong-az]

D:\fsr2-src\src\ffx-fsr2-api\dx12\ffx_fsr2_dx12.cpp(1170,31): warning C4996: 'std::codecvt_utf8_utf16<wchar_t,1114111,(std::codecvt_mode)0>': warning STL4017: std::wbuffer_convert, std::wstring_convert, and the header (containing std::codecvt_mode, std::codecvt_utf8, std::codecvt_utf16, and std::codecvt_utf8_utf16) are deprecated in C++17. (The std::codecvt class template is NOT deprecated.) The C++ Standard doesn't provide equivalent non-deprecated functionality; consider using MultiByteToWideChar() and WideCharToMultiByte() from <Windows.h> instead. You can define _SILENCE_CXX17_CODECVT_HEADER_DEPRECATION_WARNING or _SILENCE_ALL_CXX17_DEPRECATION_WARNINGS to acknowledge that you have received this warning.