It's useful to dump the guest, which named coredump so that crash
tool can be used to analysize it when guest hung up.
Let's add GuestDebuggable trait and Coredumpxxx error to support
coredump firstly.
Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
Co-authored-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
