The new progress bar in backup and restore automatically updates for each task/step. In some cases, a step may take a long time. We should add progress tracking within these steps. This will make the progress bar smoother and reduce the possibility of timeouts for larger courses.

I am attaching a trace of times in the backup run for the 'L' size test course. I've manually annotated this to mark tasks that take more than a couple of seconds with **, these are (in order of time taken):

17:01:25: backup_users_structure_step users ** 105s
16:57:54: backup_roles_structure_step course_roles** 33s
16:58:58: backup_forum_activity_structure_step forum structure** 33s
16:57:25: backup_enrolments_structure_step course_enrolments** 29s
16:58:29: move_inforef_annotations_to_final migrate_inforef** 24s
17:01:05: backup_annotate_all_user_files user_files ** 20s
17:03:10: backup_final_files_structure_step fileslist ** 11s
17:04:27: backup_store_backup_file save_backupfile ** 7s
17:03:24: backup_zip_contents zip_contents ** 3s

I'll investigate all these steps to see which ones we can add progress information for.