Remove back-port of C++17 features #357
Description
We implemented some C++17 features when we were still stuck with C++14, like ekat::any or ekat::enable_shared_from_this. Since ekat now requires C++17, all these features are available from the std library, so we should remove the hand-crafted classes. We can do a deprecation first, by doing something like
#ifndef EKAT_STD_ANY_HPP
#define EKAT_STD_ANY_HPP
#pragma warning("Warning: Including ekat_std_any.hpp is discouraged. Please avoid using ekat::any, and rely on std::any instead.")
namespace ekat {
...
}
#endif // EKAT_STD_ANY_HPP