m/c/metroctl: introduce proxyAddr parameter

This enables metroctl to interact with the cluster over a SOCKS5 proxy.

Change-Id: I73a59b01cecec7b5988ca57d7ff71179da260949
Reviewed-on: https://review.monogon.dev/c/monogon/+/830
Tested-by: Jenkins CI
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
diff --git a/metropolis/cli/metroctl/approve.go b/metropolis/cli/metroctl/approve.go
index 4a99e9d..adb7b8f 100644
--- a/metropolis/cli/metroctl/approve.go
+++ b/metropolis/cli/metroctl/approve.go
@@ -68,7 +68,7 @@
 		log.Fatal("Please provide at least one cluster endpoint using the --endpoint parameter.")
 	}
 	ctx := clicontext.WithInterrupt(context.Background())
-	cc, err := dialCluster(ctx, opkey, ocert, "", flags.clusterEndpoints)
+	cc, err := dialCluster(ctx, opkey, ocert, flags.proxyAddr, flags.clusterEndpoints)
 	if err != nil {
 		log.Fatalf("While dialing the cluster: %v", err)
 	}