Get one instance's usage

Running time and estimated cost for a single server, over the same billing period GET /v1/usage reports, with its session history. The path parameter is the instance id and appears in the body as service_id — they are the same identifier. FOUR cases all answer 404 and are deliberately indistinguishable: an id that is not a uuid, an instance belonging to another account, an instance of yours that has never run, and an offset past the end of an instance's history. Treat a 404 here as "no usage on this page", not as "no such server" — ask GET /v1/instances/{id} if you need to know whether it exists, and do not use a 404 as the stop condition when walking history.