Add args description to DatasetInfo
Thanks for the suggestions! I've included them and made a few minor tweaks along the way Please merge master into this branch to fix the CI, I just fixed metadata validation tests.
Closes #2354 

I am not sure what `post_processed` and `post_processing_size` correspond to, so have left them empty for now. I also took a guess at some of the other fields like `dataset_size` vs `size_in_bytes`, so might have misunderstood their meaning.