Unify `namespacedRef` and `konnectNamespacedRef`

[pmalek]

Problem statement

Currently, types in this repository have 2 types of references that can be used to reference another object: konnectNamespacedRef and namespacedRef.

The former is used to refer to a Konnect CP from a config object (e.g.

kubernetes-configuration/config/samples/konnect_kongservice.yaml

Lines 33 to 36 in 3ae8a30

	controlPlaneRef:
	type: konnectNamespacedRef
	konnectNamespacedRef:
	name: test1

).

The latter is used to refer to another object e.g. from a KongRoute to a KongService (https://github.com/Kong/gateway-operator/blob/38fcef4ddde9b1d24ff223f94ebada26cb400f9f/config/samples/konnect_kongroute.yaml#L49-L52).

This task tracks the design of a plan and implementation of unification of these reference types (unless a strong reason comes to light, preventing this unification).

Acceptance criteria

• As a user I can use 1 type of reference to refer to another objects in the cluster.

[sandromodarelli]

punting to KO 2.1.0 to handle priority.
this will create a breaking change in some stable APIs (like KongConsumer). we'll discuss later between some possible approaches

[pmalek]

For wider context:

This should be relatively easy to do by expanding the enums in:

• KonnectExtensionControlPlaneRef Type:

  kubernetes-configuration/api/common/v1alpha1/controlplaneref_types.go

  Line 65 in f037654

  // +kubebuilder:validation:Enum=konnectNamespacedRef

• ControlPlaneRef Type:

  kubernetes-configuration/api/common/v1alpha1/controlplaneref_types.go

  Line 38 in f037654

  // +kubebuilder:validation:Enum=konnectID;konnectNamespacedRef;kic

This will require however

• adding CRD validation tests to ensure that the added enum value is allowed by the API server
• adjusting the CRD validation rules where we check the ref type (e.g.

  kubernetes-configuration/api/konnect/v1alpha1/konnect_extension_types.go

  Line 47 in 201a3e5

  // +kubebuilder:validation:XValidation:rule="self.spec.konnect.controlPlane.ref.type == 'konnectNamespacedRef' ? !has(self.spec.konnect.configuration) : true",message="konnect must be unset when ControlPlaneRef is set to konnectNamespacedRef."

  )