Update tests with data from digitization and legacy digital workflows

[helrond]

Is your feature request related to a problem? Please describe.

In order to ensure full test coverage, we need to add fixture data (both bags and JSON) which represents the full range of bags that may be processed by Fornax.

Describe the solution you'd like

Once we have developed the infrastructure to create bags from digitized and legacy born-digital workflows, we should add samples to the test fixtures and make sure that the tests still pass.