Add filters for workloads.Pods

[smgladkovskiy]

I think that filters will be very useful:

1. show completed pods (kubectl get pod --field-selector=status.phase==Succeeded)
2. show error pods (kubectl get pod --field-selector=status.phase==Failed)
3. show running pods (kubectl get pod --field-selector=status.phase==Running)
4. show pending pods (kubectl get pod --field-selector=status.phase==Pending)