Support struct yaml

[qicosmos]

Why

Add struct_yaml:

// serialization the structure to the string
person p = {"admin", 20};
std::string ss;  // here use std::string is also ok
struct_yaml::to_yaml(ss, p);
std::cout << ss << std::endl;
std::string yaml = R"(
name : tom
age : 30
)";
// deserialization the structure from the string
struct_yaml::from_yaml(p, yaml);