Added CachedResourceSchemaSource to CachedResource

The schema source for the wrapped resource is determined before
the CachedResource object is marked as ready. The schema
may be coming from a CRD, or an APIResourceSchema. In both cases
it is cloned to CachedResource's cluster, and replicated to cache.

This serves two purposes:
* Schema is now disconnected from its original location,
  improving resiliance against provider unavailability.
* Replication VW is greatly simplified, as it does
  schema lookup in a single step.

On-behalf-of: @SAP [email protected]
Signed-off-by: Robert Vasek <[email protected]>

Author: gman0

config/crds/cache.kcp.io_cachedresources.yaml

@@ -216,6 +216,42 @@ spec:
                 - cache
                 - local
                 type: object
+              resourceSchemaSource:
+                description: ResourceSchemaSource is a reference to the schema object
+                  of the cached resource.
+                properties:
+                  apiResourceSchema:
+                    description: APIResourceSchema defines an APIResourceSchema as
+                      the source of the schema.
+                    properties:
+                      clusterName:
+                        description: ClusterName is the name of the cluster where
+                          the APIResourceSchema is defined.
+                        minLength: 1
+                        type: string
+                      name:
+                        description: Name is the APIResourceSchema name.
+                        minLength: 1
+                        type: string
+                    required:
+                    - clusterName
+                    - name
+                    type: object
+                  crd:
+                    description: CRD defines a CRD as the source of the schema.
+                    properties:
+                      name:
+                        description: Name is the CRD name.
+                        minLength: 1
+                        type: string
+                      resourceVersion:
+                        description: ResourceVersion is the resource version of the
+                          source CRD object.
+                        type: string
+                    required:
+                    - name
+                    type: object
+                type: object
             type: object
         required:
         - spec

config/root-phase0/apiexport-cache.kcp.io.yaml

@@ -12,7 +12,7 @@ spec:
       crd: {}
   - group: cache.kcp.io
     name: cachedresources
-    schema: v250523-2b8c1d3c5.cachedresources.cache.kcp.io
+    schema: v250830-080348246.cachedresources.cache.kcp.io
     storage:
       crd: {}
 status: {}

config/root-phase0/apiresourceschema-cachedresources.cache.kcp.io.yaml

@@ -2,7 +2,7 @@ apiVersion: apis.kcp.io/v1alpha1
 kind: APIResourceSchema
 metadata:
   creationTimestamp: null
-  name: v250523-2b8c1d3c5.cachedresources.cache.kcp.io
+  name: v250830-080348246.cachedresources.cache.kcp.io
 spec:
   group: cache.kcp.io
   names:
@@ -213,6 +213,42 @@ spec:
               - cache
               - local
               type: object
+            resourceSchemaSource:
+              description: ResourceSchemaSource is a reference to the schema object
+                of the cached resource.
+              properties:
+                apiResourceSchema:
+                  description: APIResourceSchema defines an APIResourceSchema as the
+                    source of the schema.
+                  properties:
+                    clusterName:
+                      description: ClusterName is the name of the cluster where the
+                        APIResourceSchema is defined.
+                      minLength: 1
+                      type: string
+                    name:
+                      description: Name is the APIResourceSchema name.
+                      minLength: 1
+                      type: string
+                  required:
+                  - clusterName
+                  - name
+                  type: object
+                crd:
+                  description: CRD defines a CRD as the source of the schema.
+                  properties:
+                    name:
+                      description: Name is the CRD name.
+                      minLength: 1
+                      type: string
+                    resourceVersion:
+                      description: ResourceVersion is the resource version of the
+                        source CRD object.
+                      type: string
+                  required:
+                  - name
+                  type: object
+              type: object
           type: object
       required:
       - spec