support PodSandboxStatusRequest for containerd_client

[liaozhaoyan]

I want to use containerd_client to inpect pod, use crictl like:

crictl -D inspectp 0eee6802021a0
DEBU[0000] PodSandboxStatusRequest: &PodSandboxStatusRequest{PodSandboxId:0eee6802021a0,Verbose:true,} 

However, it is not supported at the moment. This is a commonly used feature. I'm really looking forward to being able to support it on version 0.6, best regards.