add bliss_original_files

This is a simple add of the file converted. This is saved as a n array to handle concatenation and manual edition (like when adding some dark / flat from other datasets)

@paleo @mirone does the location / name is fine with you ? Better propositions >

warning: there is no API at tomoscan level for this as I expect the processing to be very limited and this not - required metadata for processing

@mirone does it fit your needs ?