[kotlin-client][multiplatform] Added support enum query parameter

[YusukeOba]

#13404

The above PullRequest now outputs normal code when an enum exists in the query parameter.
However, it was not supported by the kotlin-client multiplatform library.

With my PR, the kotlin-client multiplatform library now outputs correct code with query parameters with enums as well.

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[YusukeOba]

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[wing328]

https://github.com/OpenAPITools/openapi-generator/actions/runs/5865135521/job/15901497278?pr=16327 not related to this change.

[wing328]

LGTM. Thanks for the PR.