Article list ordering is slightly messed up

[hexjelly]

My fault 🤭
Currently it is ordering articles by publishedAt, then _createdAt. This does not work very well as it is now, since it will first show all the ones with publishedAt, then if an article is missing the publishedAt (old articles when it was not a required field), it will show up after all the ones with publishedAt present, even if it's newer.

I think that is what is happening, by just having a quick look at another PR surrounding the articles... maybe worth a second look to make sure I'm not making stuff up 😬

What needs to be done

Probably a "migration" where we update every article without a publishedAt would be the best, because it would be good to have it for all articles anyway. E.g. go through every article, if it does not have a publishedAt, set it to be the same as the article's _createdAt. It could be fixed in the code as well, but I think it would be better to do it this way.