Add HorizonSpecCore struct

This version of the struct (called "core") is meant to
be used via the OpenStackControlplane. It is the same
as HorizonSpec only it is missing the containerImages.

The Default() function for webhooks has been split accordingly.

Jira: OSPRH-4835

api/v1beta1/horizon_types.go

@@ -35,9 +35,15 @@ const (
 
 // HorizonSpec defines the desired state of Horizon
 type HorizonSpec struct {
+	HorizonSpecCore `json:",inline"`
+
 	// +kubebuilder:validation:Required
 	// horizon Container Image URL
 	ContainerImage string `json:"containerImage"`
+}
+
+// HorizonSpecBase -
+type HorizonSpecCore struct {
 
 	// +kubebuilder:validation:Optional
 	// +kubebuilder:default=1

api/v1beta1/horizon_webhook.go

@@ -66,9 +66,16 @@ func (r *Horizon) Default() {
 
 // Default - set defaults for this Horizon spec
 func (spec *HorizonSpec) Default() {
+    // NOTE: only containerImage validations go here
 	if spec.ContainerImage == "" {
 		spec.ContainerImage = horizonDefaults.ContainerImageURL
 	}
+	spec.HorizonSpecCore.Default()
+}
+
+// Default - set defaults for this Horizon spec core (this one gets used by OpenstackControlPlane)
+func (spec *HorizonSpecCore) Default() {
+	// nothing here yet
 }
 
 // TODO(user): change verbs to "verbs=create;update;delete" if you want to enable deletion validation.