Finds deprecated in C++17 inheritance from std::iterator and replaces it with type aliases. The check itself is not marked as C++17 because it could be applied to any project with no harm.
Because of need to catch CXXBaseSpecifier I extended clang::ast_type_traits, but locally and in a hacky way. I would be glad if someone who knows ASTMatcher internals do add a proper CXXBaseSpecifier support.