add BNL processed newspapers
This pull request adds the BNL's [processed newspaper collections](https://data.bnl.lu/data/historical-newspapers/) as a dataset. This is partly done to support BigScience see: https://github.com/bigscience-workshop/data_tooling/issues/192. 

The Datacard is more sparse than I would like but I plan to make a separate pull request to try and make this more complete at a later date. 

I had to manually add the `dummy_data` but I believe I've done this correctly (the tests pass locally). 
