Show that upload is still alive for very large files

Users can make huge uploads which can take several days via S3 (ex: test file 300gb).
At the interface level, we should add something to indicate to the user that his upload is still "alive" and not buggy.

Currently when you make a request on /complete the upload remains "blocked" at 100% until the call to FileManager.Import (where it will go to the Finalizing... state).

We forced the use of idempotent requests on Drive for large files NXDRIVE-2704. So we check every 60 seconds or so if the file is still being processed by the server.
We MUST inform the user that it's upload is still in progress so that it doesn't retry it.