Add the new option dowload file in modal + add the corresponding REST routes:

Technically:

2 new REST routes:

• POST to create the file
  • the new version is "un-published" until all chunks are uploaded. People should not be able to do any action on the "un-published" version
  • there cannot be 2 concurrent upload of version for the same file
• PATCH to send chunks
  • Last chunk is identified so the file can be marked as published
  • If file size > to a configured size, a 400 error is thrown and uploaded chunks are discarded

In addition to that, in SYSTEM_CHECK (every 30 minutes) files partially uploaded and not yet published are discarded (given a resonable delay to avoid discarding a file being currently uploaded).

We should check that non fully uploaded document are not displayed in old view.