Update RetrieveJob to support completion report

Problem to solve

In a setups where tape servers have a direct access to the storage system repository, for example due to shared cluster file system, then storage system can pass file://... as srcURL. However, as RetrieveJob doesn't report successful completion, the storage system is unaware that file restore is complete.

Stakeholders

Setups where storage system's use shared file systems, like CephFS os cluster file systems

Proposal

Update RetrieveJob logic to port successful completion if report url is provided.