[list] Copying large folders is unreliable

[auniverseaway]

We have several issues that creates instability with large (> 500 items) folder copies.

1. Fundamental issues with content integrity we (or S3 SDK) dies on - "empty" or // prefixes
2. The relationship with DA_JOBS seems brittle. I cannot reliably copy anything of meaningful size.
3. We are not resilient to "Network changed" errors that may happen on the client. Ideally the client has a way to pick up where they left off. This could be as simple as getting the continuation token and when supplying back da-admin looks at DA_JOBS to see if there's an existing job.