Wish: possibility to reference specif files within a dataset via private URL (preview URL)

[vkush]

Is needed to reference files within a dataset on the stage of a paper review - not a complete dataset, but also specific files.

As a solution can be:

1. Private URL for files (NOT IMPLEMENTED YET, feature request is needed)
2. Just a reference in the draft paper like [<private URL for dataset>, see file 1] and [<private URL for dataset>, see file 2]. When paper is accepted, the reference [<private URL for dataset>, see file 1] can be then replaced with a proper reference via PID (for the complete dataset of for the specific file).