Migrate Feed updating and build xml to new model

server/models/Series.js

@@ -54,6 +54,18 @@ class Series extends Model {
     })
   }
 
+  /**
+   *
+   * @param {string} seriesId
+   * @returns {Promise<Series>}
+   */
+  static async getExpandedById(seriesId) {
+    const series = await this.findByPk(seriesId)
+    if (!series) return null
+    series.books = await series.getBooksExpandedWithLibraryItem()
+    return series
+  }
+
   /**
    * Initialize model
    * @param {import('../Database').sequelize} sequelize