Move History to its own collection

Move History information to its own collection

Summary

Currently each item has its history embedded in itself. If the item is modified multiple times, which might happen due to the data curation process, the number of entries under the history property can grow and use a considerable amount of the 165Mb of the allowed size for the mongodb document.
That might cause race condition when the item is already big and a new update is performed, resulting in a failed update.

Current Behaviour

History is embedded in each documents

Expected Behaviour

Each history item should be stored in the History collection. One entry per update and reference the item updated and the type

No files, tests, or entry points are identified in the issue. Start by tracing how item updates currently persist embedded history and how the History collection is modeled, then determine the references and update behavior needed. Done means each update creates a History entry linked to the item and history is no longer embedded without causing document-size or update-race failures.