es-archiver call _migrate endpoint instead of creating a migrator

Author: pgayvallet

packages/kbn-dev-utils/src/kbn_client/kbn_client_saved_objects.ts

@@ -57,9 +57,28 @@ interface UpdateOptions<Attributes> extends IndexOptions<Attributes> {
   id: string;
 }
 
+interface MigrateResponse {
+  success: boolean;
+  result: Array<{ status: string }>;
+}
+
 export class KbnClientSavedObjects {
   constructor(private readonly log: ToolingLog, private readonly requester: KbnClientRequester) {}
 
+  /**
+   * Run the saved objects migration
+   */
+  public async migrate() {
+    this.log.debug('Migrating saved objects');
+
+    return await this.requester.request<MigrateResponse>({
+      description: 'migrate saved objects',
+      path: uriencode`/api/saved_objects/_migrate`,
+      method: 'POST',
+      body: {},
+    });
+  }
+
   /**
    * Get an object
    */