Add Western Europe ISO-8859-15 encoding to csv export data

I think we need to wait for this feature to be in the CSV Serialization module before we can implement the UI to allow the selection.

✨ Add support for more encodings Needs work

We'll wait to see what version of utf8 or utf-8 gets into the upstream module (at the moment it's using both) and then we'll adjust our code accordingly, and we can collect together all the great effort here on tests, update hooks etc.