Added support for a trait based reqwest Rust client

[ranger-ross]

This PR added a new reqwest-trait generator that was requested in #11319.

This implementation uses traits as the primary interface using APIs. This has 2 primary benefits

• We do not need to pass configuration::Configuration to all API calls as we now store that in the implementing struct.
• This makes mocking in tests much easier as we can implement the interface to return the desired response.

I also added 2 small QoL features in this sub-library:

• Added a mockall option (defaults to OFF) that adds the mockall crate to make testing much easier.
• Added a topLevelApiClient option (defaults to OFF) that adds a top level Api trait and ApiClient struct that serves a container. This makes managing APIs with many tags much easier as we only need to construct one client instead of many.

PR checklist

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

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

  (For Windows users, please run the script in Git BASH)
  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
• File the PR against the correct branch: master (upcoming 7.x.0 minor release - breaking changes with fallbacks), 8.0.x (breaking changes without fallbacks)
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.
  • @frol @farcaller @richardwhiuk @paladinzh @jacob-pro

[wing328]

https://github.com/OpenAPITools/openapi-generator/actions/runs/11200379712/job/31224911798?pr=19788

not related to this change

[wing328]

what about putting [features] inside the mockall mustache tags?

[ranger-ross]

@wing328 I thought about that originally, but figured it would be easier to always add [features] so adding new features in the future would be easier.

ie.

[features]
{{#mockall}}
mockall = ["dep:mockall"]
{{/mockall}}
{{#foo}}
foo = ["dep:foo"]
{{/foo}}
{{#bar}}
bar = ["dep:bar"]
{{/bar}}

But I do not have a strong opinion on this, we can change if there is a reason to 👍

[wing328]

that's ok. i may file a PR later to update it

[TroyKomodo]

Is there plan to support the useSingleRequestParameter option?

Using the reqwest-trait library vs reqwest library

Perhaps we should also look to use some sort of builder to build the structs too. Not sure if in scope. (not all options are required)

[TroyKomodo]

I went ahead and added support for the 2 things I need:

• single arguments
• builder on that single argument

changes.patch

[ranger-ross]

@TroyKomodo Thanks!
I reviewed your PR and it looks good to me. I merged it into this PR 👍

[wing328]

can you please commit the updated samples and docs one more time?

[ranger-ross]

can you please commit the updated samples and docs one more time?

Sure, I just pushed a commit rebuilding them. 👍

[wing328]

thanks for the PR

let's give it a try to see if the community has any feedback/suggestion on this new generator