Remove serializationLibrary option from Kotlin server generators

[wing328]

Remove serializationLibrary option from Kotlin server generators

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[gnu9]

Why did this change remove the serializationLibrary option from Kotlin server generators?

Adding the serializationLibrary option to the client makes sense, but removing it from the server generators?

As @svenallers noted in #13155, this change removed for the backend the support of e.g. the serializationLibrary which is used by the kotlin client generator via multiplatform option.

@wing328 could you please reply why the option was not kept for the server generators?
@nucle asked already in Feb. (#13155) why it was removed.