Better progress display: “Group xxx” for container group creation, then separate lines for containers.

For single containers, there was a single mixed line now that the group and the container have the same name.
```
 $ ./bin/docker --context acitest run nginx
[+] Running 2/2
⠿ Group strange-bartik  Created         4.2s
⠿ strange-bartik        Done            20.6s
strange-bartik
``

azure/aci.go

@@ -71,8 +71,9 @@ func createOrUpdateACIContainers(ctx context.Context, aciContext store.AciContex
 	if err != nil {
 		return errors.Wrapf(err, "cannot get container group client")
 	}
+	groupDisplay := "Group " + *groupDefinition.Name
 	w.Event(progress.Event{
-		ID:         *groupDefinition.Name,
+		ID:         groupDisplay,
 		Status:     progress.Working,
 		StatusText: "Waiting",
 	})
@@ -88,7 +89,7 @@ func createOrUpdateACIContainers(ctx context.Context, aciContext store.AciContex
 	}
 
 	w.Event(progress.Event{
-		ID:         *groupDefinition.Name,
+		ID:         groupDisplay,
 		Status:     progress.Done,
 		StatusText: "Created",
 	})

azure/backend.go

@@ -132,7 +132,7 @@ func (cs *aciContainerService) List(ctx context.Context, _ bool) ([]containers.C
 
 		if _, ok := group.Tags[singleContainerTag]; ok {
 			if group.Containers == nil || len(*group.Containers) < 1 {
-				return []containers.Container{}, fmt.Errorf("found no containers in ACI container group %s", *containerGroup.Name)
+				return []containers.Container{}, fmt.Errorf("no containers found in ACI container group %s", *containerGroup.Name)
 			}
 			container := (*group.Containers)[0]
 			c := getContainer(*containerGroup.Name, group.IPAddress, container)