Ability to track document downloads through GO

[tovari]

Some users demand more detailed analytics, esp. download counts for documents published on GO. There are 3 main document sources at the moment:

• adore
• Azure blob
• sharepoint

There might be other in the future.
Adore is not able to log downloads and this might be the case for sharepoint as well. I'm wondering, if we would be able to log any kind of download through the UI or setup Google Analytics to do this?

[szabozoltan69]

For this purpose an API endpoint should be created, similarly to:
https://github.com/the-deep/server/blob/develop/deep/urls.py#L437-L441 and
https://github.com/the-deep/server/blob/develop/apps/gallery/views.py#L115-L131

The aim is only the frontend download logging, so the Django Admin URL-s can remain as they are now.
We should find out:

• how to create the needed tokens, uuid-s and strings
• what should be the mechanism of checking
• what frontend changes are required for this functionality
• how to track the download requests
  @batpad @thenav56 @frozenhelium