添加删除ftp文件

lib/modules/meeting/controllers/meeting_connect_controller.dart

@@ -231,6 +231,7 @@ class MeetingConnectController extends GetxController {
           int previousSize = i > 0 ? listDirectory[i - 1].size ?? 0 : 0;
           FTPEntry element = listDirectory[i];
           await _downloadFile(totalSize, previousSize, element);
+          await _ftpConnect?.deleteFile(element.name);
         }
         stateStr.value = '下载完成';
         importedFilesStr.value = '下载完成，共${listDirectory.length}个文件，2秒后自动返回';