Add ECS as a named provider (#771)

                        .build(),

                )

            });

        // TODO: ECS, IMDS, and other named providers

        named_providers

            .entry("EcsContainer".into())

            .or_insert_with(|| {

                Arc::new(

                    crate::ecs::EcsCredentialsProvider::builder()

                        .configure(&conf)

                        .build(),

                )

            });

        let factory = exec::named::NamedProviderFactory::new(named_providers);

        let connector = expect_connector(conf.default_connector());

        let core_client = aws_hyper::Client::new(connector.clone());