Implement `prune()` strategy

We should implement a `prune()` strategy to remove any orphaned items.

This will be a dangerous function to use, but very important for more advanced workflows or cleanups. This function should generally work as follows:
1. Take a list of objects as input. (`List A`) We presume this will be a scan of the originating endpoint, but could be something else.
2. Scan the endpoint to be pruned and create a list of objects (`List B`)
3. For all items in `List A`, remove that item from `List B`
4. Remove all items remaining in `List B` from the endpoint to be pruned