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/readable.go

@@ -78,6 +78,11 @@ type meshStatus struct {
 	// that machine holds, with the modules that could hold it (novox/hq ADR 0207). Absent when every
 	// dependency is met. Reported, not refused, until the switch.
 	Unheld []catalogue.Unheld `json:"unheld,omitempty"`
+	// Failing is every consumer a provider says it keeps failing, with the class of error, since
+	// when, and when it was last said (novox/hq ADR 0224). Absent when no provider says so. A
+	// document without this called the mesh well while the identity provider refused every consumer
+	// for a day (04-ISSUES/179).
+	Failing []inventory.ProviderStanding `json:"failing,omitempty"`
 }
 
 // machineFiltered is one rule set on a converged machine that the mesh did not write and that
@@ -210,6 +215,7 @@ func statusAsJSON(asked answers) ([]byte, error) {
 		}
 	}
 	out.Unheld = asked.unheld
+	out.Failing = asked.failing
 	for name := range asked.refused {
 		out.Unresolved = append(out.Unresolved, machineUnresolved{
 			Node: name, Problem: asked.refused[name]})