task-debugging label files

This merge request makes SWIFT output two label files when configured with --enable-task-debugging: task_labels_task_types.txt and task_labels_task_subtypes.txt. These files contain essentially the same information as contained in swift_hardcoded_data.py, but are based on the actual task types and labels hardcoded into SWIFT, so that they are more likely to be correct.

The reason this is useful is because various forks and branches of SWIFT exist that contain different new tasks implemented by different collaborators, including a lot of people who never looked at task plots and are not aware of the existence of swift_hardcoded_data.py. I have given up on keeping track of all the different forks/branches and what changes are needed to swift_hardcoded_data.py to get the right task plot output.

To make this merge request backwards compatible, swift_hardcoded_data.py is still responsible for reading the new label files, but only if they exist.