EPIC - Introduce same non-quarkus guides for SonataFlow as we have with quarkus

[domhanak]

Summary
As we are shifting towards more java-less guides we need to introduce such examples
where no Quarkus and Java is exposed to the user.

Goal

• Introduce getting-started-with-events guide for core/handling-events-on-workflows.adoc
• Introduce getting-started-with-callbacks guide for core/working-with-callbacks.adoc
• Update reference to a guides without quarkus for core/understanding-jq-expressions.adoc
• Introduce getting-started-with-inputs for core/defining-an-input-schema-for-workflows.adoc
• Introduce getting-started-with-outputs for core/defining-an-input-schema-for-workflows.adoc
• Review any other guide and ensure we reference non-quarkus examples in non-quarkus section