Report a provider that keeps failing a consumer in status (hq ADR 0224)

The identity provider failed every consumer for a day and status called the
mesh well (hq issue 179). The controller now follows every provider's
provisioner.failing/recovered, keeps the newest failing word per provider,
machine and consumer (migration 0065), and status, its JSON and node show
name it until it recovers. Every module that receives contributions is
granted the two events, so no manifest can forget them.

cmd/mesh-controller/status.go

@@ -129,6 +129,10 @@ func printStatus(asked answers) error {
 		fmt.Println()
 	}
 
+	// A provider failing a consumer, beside machines failing what they were told: both are something
+	// not working now (novox/hq ADR 0224).
+	printFailing(asked.failing, time.Now())
+
 	if len(quiet) > 0 {
 		var said []string
 		for _, n := range quiet {
@@ -416,6 +420,12 @@ func theThreeQuestions(ctx context.Context, open *stores) (answers, error) {
 		}
 		out.unheld = append(out.unheld, plan.Unheld...)
 	}
+	// And every consumer a provider says it keeps failing (novox/hq ADR 0224). Read from what the
+	// providers announced: nothing else in the mesh knows whether a provision is being made.
+	out.failing, err = failingProviders(ctx, inv)
+	if err != nil {
+		return answers{}, err
+	}
 	out.plans, err = inv.RecentPlans(ctx, 5)
 	if err != nil {
 		return answers{}, err
@@ -528,7 +538,7 @@ func untakenModules(ctx context.Context, inv *inventory.Inventory, nodes []inven
 func (a answers) well() bool {
 	return len(a.wrong) == 0 && len(a.quiet) == 0 && len(a.behind) == 0 &&
 		len(a.waiting) == 0 && len(a.refused) == 0 && a.network == "" && len(a.untaken) == 0 &&
-		len(a.filtered) == 0 && len(a.unheld) == 0
+		len(a.filtered) == 0 && len(a.unheld) == 0 && len(a.failing) == 0
 }
 
 // hostSplit is which machines report which host version, for every version more than one machine