Fix merging for zone definitions

Without this commit, setting `metadata.labels` on a zone would delete
some important metadata such as `metadata.name`. To avoid this, we call
`com.makeMergeable()` on the user-provided partial zone object.

component/main.jsonnet

@@ -10,7 +10,8 @@ local params = inv.parameters.control_api;
 
 
 local zones = [
-  controlApi.Zone(name) + params.zones[name] {
+  controlApi.Zone(name) +
+  com.makeMergeable(params.zones[name]) {
     metadata+: {
       labels+: common.DefaultLabels,
     },

tests/defaults.yml

@@ -93,6 +93,9 @@ parameters:
 
     zones:
       example-zone-1:
+        metadata:
+          labels:
+            control.appuio.io/zone-cluster-id: c-appuio-example1
         data:
           displayName: Example Zone 1
           features:

tests/golden/defaults/control-api/control-api/20_zones.yaml

@@ -23,6 +23,7 @@ metadata:
     app.kubernetes.io/component: control-api
     app.kubernetes.io/managed-by: commodore
     app.kubernetes.io/name: control-api
+    control.appuio.io/zone-cluster-id: c-appuio-example1
     name: example-zone-1
   name: example-zone-1
 ---