Add tests for array return (typescript-nestjs-server)

[wing328]

a follow up PR to #24005

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  ./mvnw clean package || exit
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  ./bin/utils/export_docs_generators.sh || exit
  

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Summary by cubic

Adds a new Petstore test spec for typescript-nestjs-server with a GET /users endpoint returning User[], updates the config to use it, and regenerates samples. This adds the FakeApi abstract API and controller with provider wiring in ApiModule to verify array return types are handled end-to-end.

^{Written for commit a86c873. Summary will update on new commits.}