worker/server: job status struct

The number of return values from the `jobStatus`
function was growing and getting out of hand. Not
all return values were being used in all cases
and so returning a single struct with the information
and status of a job makes more sense. Then in each case
the resulting fields can be used as needed.

internal/cloudapi/v2/server.go

@@ -292,7 +292,7 @@ func generateManifest(ctx context.Context, workers *worker.Server, depsolveJobID
 		return
 	}
 
-	_, _, err = workers.DepsolveJobStatus(depsolveJobID, &depsolveResults)
+	_, err = workers.DepsolveJobStatus(depsolveJobID, &depsolveResults)
 	if err != nil {
 		reason := "Error reading depsolve status"
 		jobResult.JobError = clienterrors.WorkerClientError(clienterrors.ErrorReadingJobStatus, reason)