plugin register with artifact stubs VAULT-32686 (#29113)

* add plugin catalog's entValidate() and setInternal() oss stubs 
* create plugin register command constructor oss stub
* create EntPluginRunner oss stub
* add validateSHA256() oss stub to validate plugin catalog update input

sdk/helper/pluginutil/runner.go

@@ -57,6 +57,8 @@ const MultiplexingCtxKey string = "multiplex_id"
 // PluginRunner defines the metadata needed to run a plugin securely with
 // go-plugin.
 type PluginRunner struct {
+	EntPluginRunner
+
 	Name           string                      `json:"name" structs:"name"`
 	Type           consts.PluginType           `json:"type" structs:"type"`
 	Version        string                      `json:"version" structs:"version"`

sdk/helper/pluginutil/runner_stubs_oss.go

@@ -0,0 +1,8 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+//go:build !enterprise
+
+package pluginutil
+
+type EntPluginRunner struct{}