Display sources of datasets' files in the UI

[mohammad-alisafaee]

Is your feature request related to a problem? Please describe. As a Renku user, I would like to be able to see the origin of files that were added to datasets from URLs or external files.

Additional context See the discussion here: https://renku.discourse.group/t/adding-large-datasets/334/5?u=mohammad-sdsc. We store this information in the core for URLs but for external files we only store a path to local filesystem (and not where that external data comes from). KG does not process this data.