[Enhancement]: Add body-wrapping progress tracker example for Rust

[Velfi]

Background story

Some users want to track the progress of large uploads. We don't provide a built-in way to do this, but it's possible to write a body wrapper that accomplishes this.

Create an example that demonstrates that for a PutObject request. The resulting body should be "retryable."

Checksums are implemented with body wrappers and can probably be adapted.

• Checksum body wrapping fn
• Checksum retryability test
• SdkBody::map is the easiest way to wrap a body

What does this example accomplish?

This example will teach users how to use body wrappers in order to track the progress of uploads.

Which AWS service(s)?

S3

Which AWS SDKs or tools?

• All languages
• .NET
• Go (v2)
• Java
• Java (v2)
• JavaScript
• JavaScript (v3)
• Kotlin
• PHP
• Python
• Ruby
• Rust
• Swift
• Not applicable

Are there existing code examples to leverage?

No response

Do you have any reference code?

No response

[Velfi]

I submitted this issue on behalf of this user-submitted issue:
smithy-lang/smithy-rs#2092

I put some example code in that issue that may be helpful when implementing this example.

[github-actions]

Marked stale by the Shirriff. Notifying @awsdocs/aws-sdk-docs-code-maintainers

[DavidSouther]

This could be merged with #3209