Implement RFC #2 HTTP Versions

[Velfi]

https://github.com/awslabs/smithy-rs/blob/main/design/src/rfcs/rfc0002_http_versions.md

[Velfi]

This should be implemented after #1225. PR #1918 adds the config half of things and the implementation of RFC #2 should implement the client pooling half.

[jdisanti]

Duplicate of #1108