Add tool to format with pretty-please

[jdisanti]

Motivation and Context

This PR adds a tool that formats a cargo workspace using the dtolnay/prettyplease library to replace rustfmt since rustfmt fails to format most of our generated code now.

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[github-actions]

A new generated diff is ready to view.

• No codegen difference in the AWS SDK
• No codegen difference in the Client Test
• Server Test (ignoring whitespace)
• Server Test Python (ignoring whitespace)
• Server Test Typescript (ignoring whitespace)

A new doc preview is ready to view.

[github-actions]

A new generated diff is ready to view.

• AWS SDK (ignoring whitespace)
• Client Test (ignoring whitespace)
• Server Test (ignoring whitespace)
• Server Test Python (ignoring whitespace)
• Server Test Typescript (ignoring whitespace)

A new doc preview is ready to view.

[jdisanti]

Looks like prettyplease has a bug that the SDK triggers:

    Checking aws-sdk-transcribestreaming v0.0.0-local (/home/build/workspace/smithy-rs/aws/sdk/build/aws-sdk/sdk/transcribestreaming)
error: unnecessary trailing semicolon
  --> /home/build/workspace/smithy-rs/aws/sdk/build/aws-sdk/sdk/transcribestreaming/src/event_stream_serde.rs:17:9
   |
17 |         ; Ok(::aws_smithy_eventstream::frame::Message::new_from_parts(headers, payload))
   |         ^ help: remove this semicolon
   |
   = note: `-D redundant-semicolons` implied by `-D warnings`

Edit: Nevermind. I was quick to jump to conclusions. That's our code generator's fault. The new tool failed to run during SDK codegen, and the rustfmt had been removing this redundant semicolon.

[jdisanti]

I removed the cargo metadata workspace resolution from the tool since that was what was causing it to fail for the SDK (since it runs before the SDK copies over the runtime crates, and thus, the runtime crates don't exist when resolving the Cargo.toml files with cargo metadata). Now it just recursively formats all Rust files in a given directory.

[github-actions]

A new generated diff is ready to view.

• AWS SDK (ignoring whitespace)
• Client Test (ignoring whitespace)
• Server Test (ignoring whitespace)
• Server Test Python (ignoring whitespace)
• Server Test Typescript (ignoring whitespace)

A new doc preview is ready to view.

[jdisanti]

Judging from the codegen diff, prettyplease removes all non-doc comments. Not sure if this will work for us.

[david-perez]

Closes #1526.

This would be nice but we need it to preserve comments :(

[david-perez]

Suggested change

	"`cargo install --path tools/ci-build/please-fmt`): [${service.id}]\n${err.output}",
	"`cargo install --locked --path tools/ci-build/please-fmt`): [${service.id}]\n${err.output}",

[david-perez]

What's the benefit of this over clap?

[jdisanti]

Prettyplease doesn't preserve comments and the maintainer doesn't want to support that, so it's not a viable option for smithy-rs.