Upgrade to xsd2poet 1.0.8 with two distinct modules, one for the Java and other with the idiomatic Kotlin API. Now HtmlFlow will be free of any Kotlin dependency and only htmlflow-kotlin requires the Kotlin stdlib.

In new xsd2poet-java the ElementVisitor does not have visitSuspending anymore. Now visitSuspending is only part of the Kotlin version.

Also fix issue136.