Add snapshot label command to ctr
Add snapshot label command to ctr

Allows easier debugging of snapshots using labels

Signed-off-by: Derek McGowan <e1c79a582b6629e6b39e9679f4bb964d25db4aa8@mcgstyle.net>

vdemeester/containerd,thaJeztah/containerd,containerd/containerd,miaoyq/containerd,dmcgowan/containerd,AkihiroSuda/containerd,kunalkushwaha/containerd,mikebrow/containerd,dmcgowan/containerd,crosbymichael/containerd,estesp/containerd,miaoyq/containerd,kunalkushwaha/containerd,crosbymichael/containerd,mikebrow/containerd,containerd/containerd,vdemeester/containerd,estesp/containerd,thaJeztah/containerd