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/install.go b/metropolis/cli/metroctl/install.go
index a3657ae..cbbb9b6 100644
--- a/metropolis/cli/metroctl/install.go
+++ b/metropolis/cli/metroctl/install.go
@@ -129,7 +129,7 @@
 		if len(flags.clusterEndpoints) == 0 {
 			log.Fatal("At least one cluster endpoint is required while generating non-bootstrap installer images.")
 		}
-		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)
 		}