Add monitoring-read scope, upstreaming TPG hashicorp#2813. (hashicorp#1208)

Signed-off-by: Modular Magician <[email protected]>

Author: modular-magician

google-beta/service_scope.go

@@ -15,6 +15,7 @@ func canonicalizeServiceScope(scope string) string {
 		"datastore":             "https://www.googleapis.com/auth/datastore",
 		"logging-write":         "https://www.googleapis.com/auth/logging.write",
 		"monitoring":            "https://www.googleapis.com/auth/monitoring",
+		"monitoring-read":       "https://www.googleapis.com/auth/monitoring.read",
 		"monitoring-write":      "https://www.googleapis.com/auth/monitoring.write",
 		"pubsub":                "https://www.googleapis.com/auth/pubsub",
 		"service-control":       "https://www.googleapis.com/auth/servicecontrol",