cluster: introduce Machine.Inactive flag

if a Machine is Inactive, it won't be included on the DNS
aliases for the zone or it's regions.

Signed-off-by: Alejandro Mery <amery@jpi.io>

cmd/jpictl/dns.go

@@ -52,7 +52,7 @@ func populateDNSManager(mgr *dns.Manager, m *cluster.Cluster) error {
 
 	m.ForEachZone(func(z *cluster.Zone) bool {
 		z.ForEachMachine(func(p *cluster.Machine) bool {
-			err = mgr.AddHost(ctx, z.Name, p.ID, true, p.PublicAddresses...)
+			err = mgr.AddHost(ctx, z.Name, p.ID, p.Active(), p.PublicAddresses...)
 			return err != nil
 		})