[kotlin-client] Add ktor library with Jackson and GSON processing support

[vlsergey]

In future kotlinx serialization shall be added.

I'm not sure if this library shall supersede "multiplatform" library or leave it as it is. But ktor+jackson shall be present for sure.

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/utils/export_docs_generators.sh
  

  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.
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  For Windows users, please run the script in Git BASH.
• File the PR against the correct branch: master (5.3.0), 6.0.x
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  • @jimschubert , @dr4ke616 , @karismann , @Zomzog , @andrewemery , @4brunu , @yutaka0m

[wing328]

Tested locally and the result is good.

CircleCI failure not related to this change.

[wing328]

FYI. I've updated GitHub workflow to test the new samples via ee038e7