Add fallback equality on noAuth scheme ID

[ysaito1001]

Motivation and Context

Implements fallback equality for no auth AuthSchemeId so that AuthSchemeId::from("no_auth") (legacy) and AuthSchemeId::from("noAuth") (updated) should be treated as equivalent.

Description

In #4203, the internal raw strings of pre-defined AuthSchemeId were updated to better align with the Smithy spec (discussion). Acknowledging that this was a breaking change and that customers should not rely on these internal representations, we did receive reports of issues related to this update. After discussion, we proceeded with implementing fallback equality for no auth scheme ID to allow for a safer rollout.

Testing

• Added unit tests for manually implemented traits for AuthSchemeId, PartialEq, Hash, and Ord (became unnecessary after 7922ef9)
• Added an auth scheme preference test to verify the legacy no_auth is supported

Checklist

• For changes to the smithy-rs codegen or runtime crates, I have created a changelog entry Markdown file in the .changelog directory, specifying "client," "server," or both in the applies_to key.
• For changes to the AWS SDK, generated SDK code, or SDK runtime crates, I have created a changelog entry Markdown file in the .changelog directory, specifying "aws-sdk-rust" in the applies_to key.

---

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

[github-actions]

A new generated diff is ready to view.

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

A new doc preview is ready to view.

[landonxjames]

One potential suggestion for a log, but no blockers

[github-actions]

A new generated diff is ready to view.

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

A new doc preview is ready to view.