Add scalafmt (plugin) to scala-akka client generator

[Desel72]

Adds scalafmt (.scalafmt.conf) and sbt-scalafmt plugin to the scala-akka client generator for consistent code formatting.

Follows the pattern established in #23273 for scala-sttp4.

Refs #23274

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 || exit
  ./bin/generate-samples.sh ./bin/configs/scala-akka.yaml || exit
  

  Commit all changed files.
• File the PR against the correct branch: master
• If your PR solves a reported issue, reference it using GitHub's linking syntax
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

---

Summary by cubic

Adds Scalafmt to the scala-akka client generator to ensure consistent formatting by generating a .scalafmt.conf and enabling the sbt-scalafmt plugin.

• New Features
  • Generate project/plugins.sbt with sbt-scalafmt version 2.5.6.
  • Generate .scalafmt.conf (Scalafmt 3.10.6, Scala 2.13 dialect) via template.
  • Register both files in ScalaAkkaClientCodegen supporting files.
  • Update Scala Akka sample to include the new files.

^{Written for commit 6171846. Summary will update on new commits.}

[Desel72]

Hi @wing328 I opened first PR. could you review it and share any feedback?

[cubic-dev-ai]

No issues found across 6 files

---

Since this is your first cubic review, here's how it works:

• cubic automatically reviews your code and comments on bugs and improvements
• Teach cubic by replying to its comments. cubic learns from your replies and gets better over time
• Add one-off context when rerunning by tagging @cubic-dev-ai with guidance or docs links (including llms.txt)
• Ask questions if you need clarification on any suggestion

[wing328]

merged via #23299 (you as co-author) with updated tests.

thanks for the contribution.

[Desel72]

Hi @wing328, thank you for your response. However, I was hoping to have a merged PR on my account rather than a closed one or just the contributor badge.
If possible, could you help merge my PR this time, or reopen it and merge it? If it cannot be merged as is, I would be happy to update it or use it for other generators.
I would appreciate your reply. Thank you.

[wing328]

However, I was hoping to have a merged PR on my account

can you file a PR to update the following scala client generator with the scalafmt plugin?

https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ScalaHttp4sClientCodegen.java

i'll let you deal with any issues that come up and have your PR merged .

[Desel72]

@wing328 I will Open PR soon. thank you.