Self-check strategy

[CCharlieLi]

After the connection established between Pixhawk and companion computer, we need to do self check to make sure that Pixhawk is initialized and working well. Only after that, we are sure that Pixhawk is ready. As I'm not a expert of Pixhawk, @Innoecho If you have any advice?

For what I see, the check flow should be like: connect -> check/print all attributes -> check all parameters -> ???