add v1alpha2 registry based conversion (#1006)

* add v1alpha2 registry based conversion

* test defaults, set our 1st explicit default

* fix typos and dates

* move pluginregistry to its own dir

* remove unused v1alpha2.Namespace type

* move migration code folders, remove switch

* validate internalPolicy a single time

* remove structured logs

* simplify return

* check for nil methods

* properly check before adding default evictor

* add TODO comment

* bump copyright year

pkg/api/v1alpha2/doc.go

@@ -0,0 +1,24 @@
+/*
+Copyright 2023 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// +k8s:deepcopy-gen=package,register
+// +k8s:conversion-gen=sigs.k8s.io/descheduler/pkg/api
+// +k8s:defaulter-gen=TypeMeta
+
+// Package v1alpha2 is the v1alpha2 version of the descheduler API
+// +groupName=descheduler
+
+package v1alpha2 // import "sigs.k8s.io/descheduler/pkg/api/v1alpha2"