Rust: Support Integer enums using Serde_repr

[bertkdowns]

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This #9976 solved this issue but was never merged. This PR incorporated the same changes, and updates it to work with the current version of the app.

closes #9967, closes #18840

An example from my app: The following couldn't be used, because it expected strings as explained in #18840

Now, it generates to integer enums as expected:

First time contributor - LMK if there's anything else I've missed or need to do :)

[bertkdowns]

Agreed, that's much cleaner. Wasnt sure how to remove that, i've updated, synced with master, and re-gen the apis, so hopefully all the workflows should pass now too.

[wing328]

hmm... why there are changes to kotlin samples?

in the latest msater, the samples are up-to-date. can you please merge the latest master into your branch and regenerate the samples?

[bertkdowns]

Hmm, that's strange, I already did that and merging with master is what caused the kotlin examples to change for me. Perhaps it's an environment thing (I'm using the devcontainers environment and bin/generate-samples.sh) , or i'll try rollback to an earlier commit where the changes don't happen.

[wing328]

can you please add a test spec for integer enum to modules/openapi-generator/src/test/resources/3_0/rust/petstore.yaml (and regenerate the samples) so that the CI can test it moving forward?

[bertkdowns]

Ok, I think I've added those tests correctly - just involved updating the yaml file, so that the CI can check that it build correctly right? And dropped those changes to the kotlin files, must be an environment issue on my end

[ogtn]

Thanks a lot for that PR !