metropolis/cli/metroctl: add cert export command

To scrape metrics we currently need the owner certificate in a usable format.

Change-Id: Ic6695b14a764d71d9c7b698c113fe0109d5820bf
Reviewed-on: https://review.monogon.dev/c/monogon/+/1932
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
Tested-by: Jenkins CI
diff --git a/metropolis/cli/metroctl/BUILD.bazel b/metropolis/cli/metroctl/BUILD.bazel
index de7b759..3b6dc25 100644
--- a/metropolis/cli/metroctl/BUILD.bazel
+++ b/metropolis/cli/metroctl/BUILD.bazel
@@ -3,6 +3,7 @@
 go_library(
     name = "metroctl_lib",
     srcs = [
+        "cmd_certs.go",
         "cmd_install.go",
         "cmd_k8s_configure.go",
         "cmd_k8scredplugin.go",