Migrate test objects from Hyrax to Discovery Storage

[gwiedeman]

• We'll need a small but diverse set of test objects, so we may as well do some initial migration steps and get some real-world examples
• This is blocked by the lack of a specification for the Discovery Storage (SPE_DAO)

[gwiedeman]

This is half-done in the Hyrax repo.

I'm getting memory issues when exporting video. We don't have to export them this way, and there's <50 of them so it just skips exporting the files for now an just writes metadata.yml. This needs more work, as it could also silently fail to export other files.

Also needs better logging so we can verify we're getting everything on export.