kube: move cert-manager resources to kube.local.libsonnet

This way kubernetes consumers don't have to import anything from
cluster/, hopefully.

We also create a small abstraction for local additions for
kube.libsonnet without having to modify upstream.

Change-Id: I209095781f91c8867250a647fe944370cddd67d0
diff --git a/cluster/kube/lib/registry.libsonnet b/cluster/kube/lib/registry.libsonnet
index 5272b2d..d457830 100644
--- a/cluster/kube/lib/registry.libsonnet
+++ b/cluster/kube/lib/registry.libsonnet
@@ -5,7 +5,6 @@
 #    kubectl get secrets rook-ceph-object-user-<ceph-pool>-object-registry -n <ceph-namespace> -o yaml --export | kubectl replace -f - -n registry
 
 local kube = import "../../../kube/kube.libsonnet";
-local cm = import "cert-manager.libsonnet";
 
 {
     Environment: {
@@ -29,13 +28,13 @@
 
         namespace: kube.Namespace(cfg.namespace),
 
-        registryIssuer: cm.Issuer("registry-issuer") {
+        registryIssuer: kube.Issuer("registry-issuer") {
             metadata+: env.metadata("registry-issuer"),
             spec: {
                 selfSigned: {},
             },
         },
-        authCertificate: cm.Certificate("auth") {
+        authCertificate: kube.Certificate("auth") {
             metadata+: env.metadata("auth"),
             spec: {
                 secretName: "auth-internal",
@@ -46,7 +45,7 @@
                 commonName: "auth.registry",
             },
         },
-        registryCertificate: cm.Certificate("registry") {
+        registryCertificate: kube.Certificate("registry") {
             metadata+: env.metadata("registry"),
             spec: {
                 secretName: "registry-internal",