Import workflow

Jira story: https://osraav.atlassian.net/browse/OSRA-70

Implemented Orphan List Upload => Validate => Import workflow.

- https://osraav.atlassian.net/browse/OSRA-164

- https://osraav.atlassian.net/browse/OSRA-165
In each of these places, I need to assign a different object to @pending_orphan_list. In upload, I just need an empty new PendingOrphanList object, in validate, I want it created with the uploaded file and in import, I want to retrieve if from the db.

So, if I want to refactor and use a single method for all these cases, then I have to branch to return an appropriate object based on the controller method that called. I don't see why that would be better than the way I'm doing it here. If I'm misunderstanding what you meant in the comment, please let me know.