Optimize ImagesToCoordinates with `Parallel`

[JulioAPeraza]

Summary

Parallelize the for loop:

NiMARE/nimare/transforms.py

Line 370 in edbbe19

for _, row in images_df.iterrows():

Additional details

For large datasets like Neurovault, ImagesToCoordinates takes a lot of time to estimate the coordinates for all the images. It will be nice to run this process in parallel.

Next steps