Redefined vars should be marked as inherited so that override modifier is added on children class.

Changes where done in org.openapitools.codegen.languages.AbstractKotlinCodegen#fromModel by adding redefined vars to the map of vars that will be marked as inherited when the model has a parent.

Validated with a Test in org.openapitools.codegen.kotlin.KotlinClientCodegenModelTest

cc @karismann (2019/03) @Zomzog (2019/04) @andrewemery (2019/10) @4brunu (2019/11) @yutaka0m (2020/03) @stefankoppier (2022/06) @e5l (2024/10) 😊

Closes #22216

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