support all options of kubectl port-forward

- [x] kubectl port-forward mypod 5000 6000
Listen on ports 5000 and 6000 locally, forwarding data to/from ports 5000 and 6000 in the pod
- [x] kubectl port-forward mypod 8888:5000
Listen on port 8888 locally, forwarding to 5000 in the pod
- [ ] kubectl port-forward mypod :5000
Listen on a random port locally, forwarding to 5000 in the pod