Move framework ssh code to new package

The framework/ssh.go code was heavily used throughout the framework
and could be useful elsewhere but reusing those methods requires
importing all of the framework.

Extracting these methods to their own package for reuse.

Only a few methods had to be copied into this package from the
rest of the framework to avoid an import cycle.

test/e2e/framework/nodes_util.go

@@ -25,9 +25,10 @@ import (
 	"sync"
 	"time"
 
-	"k8s.io/api/core/v1"
+	v1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/util/wait"
 	clientset "k8s.io/client-go/kubernetes"
+	e2essh "k8s.io/kubernetes/test/e2e/framework/ssh"
 )
 
 // EtcdUpgrade upgrades etcd on GCE.
@@ -351,7 +352,7 @@ func (k *NodeKiller) kill(nodes []v1.Node) {
 			defer wg.Done()
 
 			Logf("Stopping docker and kubelet on %q to simulate failure", node.Name)
-			err := IssueSSHCommand("sudo systemctl stop docker kubelet", k.provider, &node)
+			err := e2essh.IssueSSHCommand("sudo systemctl stop docker kubelet", k.provider, &node)
 			if err != nil {
 				Logf("ERROR while stopping node %q: %v", node.Name, err)
 				return
@@ -360,7 +361,7 @@ func (k *NodeKiller) kill(nodes []v1.Node) {
 			time.Sleep(k.config.SimulatedDowntime)
 
 			Logf("Rebooting %q to repair the node", node.Name)
-			err = IssueSSHCommand("sudo reboot", k.provider, &node)
+			err = e2essh.IssueSSHCommand("sudo reboot", k.provider, &node)
 			if err != nil {
 				Logf("ERROR while rebooting node %q: %v", node.Name, err)
 				return