fn: Status should expose if data was served from cache. (#1123)

This is useful in scenarios where gRPC client might want
to reliably observe/report the status latency metrics
and remove any possible duplicates. If the status query
was served from cache, then these latencies show last
execution latency.

api/agent/pure_runner.go

@@ -805,6 +805,7 @@ func (pr *pureRunner) handleStatusCall(ctx context.Context) (*runner.RunnerStatu
 
 		pr.status.lock.Unlock()
 
+		cacheObj.Cached = true
 		cacheObj.Active = atomic.LoadInt32(&pr.status.inflight)
 		return &cacheObj, nil
 	}