Table data columns: show more information about imported data (`rev`, `source`, etc)

When a data file has been imported/updated using the `--rev` option of `dvc import`/`dvc update` , a `rev` subfield is being added to the `.dvc` file (See [Example: Importing and updating fixed revisions](https://dvc.org/doc/command-reference/import#example-importing-and-updating-fixed-revisions)).

I think that, in cases where it exists, showing or allowing to show the value of `rev` could be more useful than `size` which is the one being currently displayed in the "column view".