Add Clone impl to PresignedRequest (#3084)

## Motivation and Context
This makes it easier to convert presigned request into an HTTP request

## Description
<!--- Describe your changes in detail -->
- add clone impl
- add `make_presigned_request` that borrows from self

## Testing
CI
## Checklist
<!--- If a checkbox below is not applicable, then please DELETE it
rather than leaving it unchecked -->
- [ ] I have updated `CHANGELOG.next.toml` if I made changes to the
smithy-rs codegen or runtime crates
- [ ] I have updated `CHANGELOG.next.toml` if I made changes to the AWS
SDK, generated SDK code, or SDK runtime crates

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