Load attachment data when handling file renaming on item metadata change

File renaming has a Notifier handler for item modifications that needs
best-attachment titles, but attachments and their item data might not be
loaded even when parent items are. (This came up when migrating fields
from Extra after a global schema update before the main window had
loaded.)

chrome/content/zotero/renameFiles.mjs

@@ -285,6 +285,7 @@ export function registerAutoRenameFileFromParent() {
 					}
 				}
 
+				await attachmentItem.loadDataType('itemData');
 				let previousMetadataBaseName = Zotero.Attachments.getFileBaseNameFromItem(
 					parentItemBefore, { attachmentTitle: attachmentItem.getField('title') }
 				);

chrome/content/zotero/xpcom/data/item.js

@@ -3921,7 +3921,7 @@ Zotero.Item.prototype.getBestAttachments = async function () {
 		+ "AND IA.itemID NOT IN (SELECT itemID FROM deletedItems) "
 		+ "ORDER BY contentType='application/pdf' DESC, value=? DESC, dateAdded ASC";
 	var itemIDs = await Zotero.DB.columnQueryAsync(sql, [this.id, url]);
-	return this.ObjectsClass.get(itemIDs);
+	return await this.ObjectsClass.getAsync(itemIDs);
 };