feat(rust): support various Rust integer types

[thrykol]

• Added CLI option to prefer unsigned integers
• Added CLI option to down cast integers to their best fit
• toParamName now lower cases to adhere to rustfmt
• Added unit tests around all new features

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• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
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  ./mvnw clean package 
  ./bin/generate-samples.sh
  ./bin/utils/export_docs_generators.sh
  

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[BroderickCarlin]

what is this change for?

[thrykol]

Doh... thought I had reverted that. It's the result of one of the scripts they want ran before a PR. I'll revert it and then merge.