s3 tm upload req resp (#3761)

## Description
Follow up PR to #3756 that
is one part of an initial multipart upload support.

This PR is simple, it just defines new request and response types for
the upload API. These are nearly identical to what is found in the
`aws_sdk_s3` crate with the exception of the body type that leverages
the new `InputStream` type (naming bikeshed still planned for later) for
the body rather than `ByteStream`.

----

_By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice._

aws/hll/aws-s3-transfer-manager/src/lib.rs

@@ -29,5 +29,7 @@ pub mod download;
 pub mod error;
 
 /// Types and helpers for I/O
-#[allow(unused)]   // FIXME(aws-sdk-rust#1159) - remove when consumed internally by other modules
 pub mod io;
+
+/// Abstractions for downloading objects from Amazon S3
+pub mod upload;

aws/hll/aws-s3-transfer-manager/src/upload.rs

@@ -0,0 +1,14 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+pub use crate::upload::request::UploadRequest;
+pub use crate::upload::response::UploadResponse;
+
+
+/// Request types for uploads to Amazon S3
+pub mod request;
+
+/// Response types for uploads to Amazon S3
+pub mod response;