use plugin registry and prepare for conversion (#1003)

* use plugin registry and prepare for conersion

* Register plugins explicitly to a registry

* check interface impl instead of struc var

* setup plugins at top level

* treat plugin type combinations

* pass registry as arg of V1alpha1ToInternal

* move registry yet another level up

* check interface type separately

pkg/framework/plugins/removeduplicates/types.go

@@ -22,8 +22,8 @@ import (
 // +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object
 
 type RemoveDuplicatesArgs struct {
-	metav1.TypeMeta
+	metav1.TypeMeta `json:",inline"`
 
-	Namespaces        *api.Namespaces
-	ExcludeOwnerKinds []string
+	Namespaces        *api.Namespaces `json:"namespaces"`
+	ExcludeOwnerKinds []string        `json:"excludeOwnerKinds"`
 }