Allow users to see certain supporting files within Uwazi

[RafaPolit]

Is your feature request related to a problem? Please describe. Users are resorting to uploading multiple primary documents in the same language, just because they want to be able to see the PDF inside Uwazi instead of having to download every supporting file.

Describe the solution you'd like We should be able to see supporting files of "known" types inside Uwazi: see an image without having to download it, see a PDF without having to download it, present a video without having to download it.

Additional context This opens questions as to: 'should this also mean that we could have text relationships to supporting files'? So, yeah, I wouldn't do that as an MVP, but we should elaborate on the matter.

[txau]

The modal option for quick viewing could be a small intervention that helps a lot.