Problem:

When the file download controllers start their various checks on if a file is downloadable and authorized to download, there is a check to see if the file exists. This check should really occur after we have checked to see if the end user is authorized to read the dataset.

Acceptance Criteria:

The check for authorization to a file needs to occur prior to seeing if the file exists.

Note: Doing this work after removing the logical file id based URLs will reduce work. If so, we can change our auth-z checks to only be on dataset (and not also on file).