Add device information to integration tests

[johnsonw]

Add device information loaded into IML. This will allow the tests to
verify that the devices have been loaded before attempting to add
servers.

Signed-off-by: johnsonw wjohnson@whamcloud.com

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This change is 

[ip1981]

I am just pondering: :)

loop {
  count += 1;

  let iml_devices: BTreeSet<String> = get_iml_devices(config).await?;
  let all_volumes_accounted_for = wwids.is_subset(&iml_devices);
  
  println!("Comparing iml devices to bindings files ({})", &count);
  println!("iml_devices: {:?}", iml_devices);
  println!("binding wwids: {:?}", wwids);

  if all_volumes_accounted_for {
    return Ok();
  }
  if count >= max_tries {
    return Err(..);
  }
  delay_for(Duration::from_secs(5)).await;
}

[johnsonw]

Yeah this could probably be updated. Looks a bit cleaner.