Fix explicit KSerializer's name & generation when used in container

[hrach]

This PR fixes two issues for explicit generation of KSerializer for enums (with auto unknown case):

• KSerializer's name - the referencing side was ok, but the referenced side was using the wrong variable (output shows the change)
• When the enum was a part of the container, the KSerializer was generated incorrectly (non-compiling). I copied the pattern from line 123 and it works flawlessly now. I am unable to show it in the generated code without changing pets schema.

@e5l

THIS IS FOLLOW UP FOR #20092

Example of the second issue:

Before:

@Serializable
data class CreatorFanclubPutRequestBodyDto (
    @SerialName(value = "creator_fanclub_types")
    val creatorFanclubTypes: kotlin.collections.List<CreatorFanclubPutRequestBodyDto.CreatorFanclubTypes>

) {
    @Serializable(with = CreatorFanclubTypesSerializer::class)
    enum class CreatorFanclubTypes(val value: kotlin.String) {
        @SerialName(value = "actors") ACTORS("actors"),
        @SerialName(value = "actresses") ACTRESSES("actresses"),
        @SerialName(value = "unknown_default_open_api") UNKNOWN_DEFAULT_OPEN_API("unknown_default_open_api");
    }

    internal object CreatorFanclubTypesSerializer : KSerializer<CreatorFanclubTypes> {
        override val descriptor = kotlin.collections.List&lt;kotlin.String&gt;.serializer().descriptor

        override fun deserialize(decoder: Decoder): CreatorFanclubTypes {
            val value = decoder.decodeSerializableValue(kotlin.collections.List&lt;kotlin.String&gt;.serializer())
            return CreatorFanclubTypes.values().firstOrNull { it.value == value }
                ?: CreatorFanclubTypes.UNKNOWN_DEFAULT_OPEN_API
        }

        override fun serialize(encoder: Encoder, value: CreatorFanclubTypes) {
            encoder.encodeSerializableValue(kotlin.collections.List&lt;kotlin.String&gt;.serializer(), value.value)
        }
    }
}

After:

@Serializable
data class CreatorFanclubPutRequestBodyDto (
    @SerialName(value = "creator_fanclub_types")
    val creatorFanclubTypes: kotlin.collections.List<CreatorFanclubPutRequestBodyDto.CreatorFanclubTypes>
) {
    @Serializable(with = CreatorFanclubTypesSerializer::class)
    enum class CreatorFanclubTypes(val value: kotlin.String) {
        @SerialName(value = "actors") ACTORS("actors"),
        @SerialName(value = "actresses") ACTRESSES("actresses"),
        @SerialName(value = "unknown_default_open_api") UNKNOWN_DEFAULT_OPEN_API("unknown_default_open_api");
    }

    internal object CreatorFanclubTypesSerializer : KSerializer<CreatorFanclubTypes> {
        override val descriptor = kotlin.String.serializer().descriptor

        override fun deserialize(decoder: Decoder): CreatorFanclubTypes {
            val value = decoder.decodeSerializableValue(kotlin.String.serializer())
            return CreatorFanclubTypes.values().firstOrNull { it.value == value }
                ?: CreatorFanclubTypes.UNKNOWN_DEFAULT_OPEN_API
        }

        override fun serialize(encoder: Encoder, value: CreatorFanclubTypes) {
            encoder.encodeSerializableValue(kotlin.String.serializer(), value.value)
        }
    }
}

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[e5l]

Hey @hrach, thank you for the PR. Looks good