pkg/payload/task: Handle MultipleErrors in SummaryForReason

The MultipleErrors reason landed in c2ac20f (status: Report the
operators that have not yet deployed, 2019-04-09, #158), but for some
reason was left out of SummaryForReason.  I'm adding it in this commit
to get something more useful than:

  $ oc adm upgrade
  info: An upgrade is in progress. Unable to apply 4.8.0-0.ci-2021-05-26-172803: an unknown error has occurred: MultipleErrors

when the Failing=True message is:

  Multiple errors are preventing progress:
  * Cluster operator machine-api is updating versions
  * Cluster operator openshift-apiserver is updating versions

I'm not entirely clear on why these didn't fallback to the "unknown
error" strings at the bottom of SummaryForReason, but they don't seem
to have done so.

Author: wking

pkg/payload/task.go

@@ -264,6 +264,11 @@ func SummaryForReason(reason, name string) string {
 			return fmt.Sprintf("the workload %s cannot roll out", name)
 		}
 		return "a workload cannot roll out"
+	case "MultipleErrors":
+		if len(name) > 0 {
+			return fmt.Sprintf("the workload %s cannot roll out", name)
+		}
+		return "multiple errors reconciling the payload"
 	}
 
 	if strings.HasPrefix(reason, "UpdatePayload") {