Add reportlets to document run-wise DWI and anatomical file information

[tsalo]

Summary

A few thoughts:

• Phase encoding direction
• Voxel size
• TR
• Number of directions
• Number of unique bvals

[mattcieslak]

Usually the PEDs have been merged during preprocessing, so there will be a mix of PEDs in the preprocessed data. And I don't think the TR is stored in the derivatives of qsiprep, so we'd need to grab that from the raw bids.

The number of directions and the unique bvals would be very useful though