create script to generate csvs

[toloudis]

Each dataset should also generate a csv file with the feature data, containing the following per-row:
cell id, fov id (needed?), each feature value, downloadable file path to cell ome-tiff, downloadable file path to fov ome-tiff (needed?)

Column names for features should be the feature names (or keys?) from the feature defs json file.
also as a proposal:

cell_id
fov_id
cell_download_url
fov_download_url

[toloudis]

@lynwilhelm @meganrm I've added this task as I believe it's a dependency for allen-cell-animated/cell-feature-explorer#117

[toloudis]

This is worked around for the time being because we have csv data that is distributed independently via Quilt.

Generally that csv is considered to be a superset of the features we show in CFE, but as far as I know, it does not contain download links to image data! A csv generated by scripts in this repo could integrate that data as well.