KotlinInterfaceTypeGenerator - fields with @skipcodegen directive are not filtered out

[arturs678]

When applying the @skipcodegen directive to interface fields, they are still present in the generated code.

Fields with @skipcodegen should be filtered out at this point: https://github.com/Netflix/dgs-codegen/blob/0ed16ad23cbeb145a553adfe159118362d2c79da/graphql-dgs-codegen-core/src/main/kotlin/com/netflix/graphql/dgs/codegen/generators/kotlin/KotlinInterfaceTypeGenerator.kt#L60