This PR contains the proposed solution to #22356 - introducing an optional useSerdePathToError config option for the Rust generator (defaulting to false) that adds the serde_path_to_error library for improving Serde error responses. The linked issue contains an example before / after error message.

Change breakdown:

• Add a useSerdePathToError config option to the Rust generator
• Add a conditional serde_path_to_error = "^0.1" dependency
• Add a conditional SerdePathToError error type and all appropriate methods
• Conditionally switch the main API response parse between serde_json::from_str and the appropriate serde_path_to_error equivalent
• Add a new sample: samples/client/petstore/rust/reqwest/petstore-serde-path-to-error

Notably, I'm leaving the 4XX/5XX-path serde_json::from_str untouched. This path will include the both the received raw response body and (if parseable) the JSON response body. This should improve debug-ability sufficiently to not need this additional library.

PR checklist

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• Run the following to build the project and update samples:

  ./mvnw clean package || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

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  Commit all changed files.
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