New cppstd for apple-clang

[czoido]

Docs for conan-io/conan#13185

[SSE4]

why exception is needed? if non-default C++ standard is needed, it could be always specified explicitly in profile.
otherwise, I think conan v2 should avoid these sophisticated workarounds and just return whatever compiler reports as is, without any adjustments. otherwise, it would cause a lot of reports like "my compiler default is X but conan reports Y", which is a huge source of confusion.