The database model is a class "database" which contains a map of collection_ids to "collection"s we should split out the keys and values held in those collections to a separate location for usage in the validation stage of the test.

This will allow us to replace the mutex with an atomic and remove the mutex from the collection class.

Having them in the same location has caused some confusion, it also appears that we can remove a redundant map from the model, either keys or values.