Add minimally-preprocessed Cohen dataset to datasets module

[tsalo]

Summary

One dataset we may want to include in the new datasets module is Multiband Multi-Echo Simultaneous ASL/BOLD for task-induced functional MRI.

Additional Detail

We'll need to run fMRIPrep on this dataset and then upload it to the OSF (or wherever).

Next Steps

1. Determine preferred location for data.
2. Add data to location.
3. Build manifest (not sure how this is done).
4. Add new dataset to datasets module.