Add DELETE with body to kotlin client

[oharaandrew314]

PR checklist

• Read the contribution guidelines.
• Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh, ./bin/openapi3/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows\. If contributing template-only or documentation-only changes which will change sample output, be sure to build the project first.
• Filed the PR against the correct branch: master, 4.1.x, 5.0.x. Default: master.
• Copied the technical committee to review the pull request if your PR is targeting a particular programming language.

@jimschubert @dr4ke616 @karismann @Zomzog

Description of the PR

Closes #4046

[wing328]

Thanks for the PR but your commit (as shown in the Commits tab) is not linked to your Github account, which means this PR won't count as your contribution in https://github.com/OpenAPITools/openapi-generator/graphs/contributors.

Let me know if you need help fixing it.

Ref: https://github.com/OpenAPITools/openapi-generator/wiki/FAQ#how-can-i-update-commits-that-are-not-linked-to-my-github-account

[oharaandrew314]

@wing328 Thanks, I added the email to my account. Now the commits are recognized as me.

I updated the sample that circle CI complained about. Hopefully we're good to go after that.

[oharaandrew314]

It would appear that all recent travis builds are failing. Seems to be a broken dependency for valgrind.

[oharaandrew314]

Re-opening to re-run builds. Seems like travis might be fixed now.

[wing328]

The travis issue has been fixed in the master so don't worry about it.

[wing328]

@oharaandrew314 thanks for the PR, which has been included in v4.2.0 release: https://twitter.com/oas_generator/status/1189824932345069569