[typescript-fetch] fix circular imports being generated

[BeryJu]

templates based off of #6140 and @ajaska

closes #6140

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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• File the PR against the correct branch: master (5.3.0), 6.0.x
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

@TiFu (2017/07) @taxpon (2017/07) @sebastianhaas (2017/07)
(I didn't want to mention all people at once so I just took the first three)

[amakhrov]

I didn't want to mention all people at once so I just took the first three

you never know who's still active though :). so it's usually more reliable to copy-paste the full list.
the rest:
@kenisteward (2017/07) @Vrolijkx (2017/09) @macjohnny (2018/01) @topce (2018/10) @akehir (2019/07) @petejohansonxo (2019/11) @amakhrov (2020/02)

[amakhrov]

Thanks for the fix - looks good to me.

There seems to be smth off with CI - the failure doesn't look related to the changes in the PR

[torkleyy]

Fixes the issue for me as well 👍