[Epic] ETH LTS Interface

[phwissmann]

As a developer, I want an interface to copy data to the LTS, validates the copy and returns the state of the process when it has finished; similarly, I want to be able to trigger a retrieval and get the data once it is ready. The interface should be abstracted from the actualy LTS implementation.

• POC: Archiving on ETH LTS #3
• Implement archival operation against mock #17
• Implement retrieval operation against mock #18
• Verify LTS interface implementation against test LTS share #19