Add option to download a published authors CSV from the console

[briangow]

This adds another download option on top of what was introduced in #2270 . It gives the option to download all of the published author objects and related data.

I've included all the base PublishedAuthor fields and have linked to a couple of other relevant fields (user_id, project_id, etc.). I'm happy to add / remove fields as desired.

[tompollard]

Thanks! Looks good to me, once the style issue is resolved.

Not sure we need author.pk (it might even be the same as author.id?).

[tompollard]

Oh sorry, one small thing:

', '.join([a.name for a in author.affiliations.all()]), might need a bit more thought because affiliations include commas. It will be difficult to work out where one affiliation ends and the other starts.

[briangow]

Thanks @tompollard , I've removed the primary key from the CSV output and now delimit multiple affiliations by using a semi-colon.

[tompollard]

Addresses one of the points in: #2277