Agentic Workflows Support

[ricardozanini]

What would you like to be added:
After LangChain4j support, we need a few improvements on the DSL and agentic use cases side.

Why is this needed:

1. Add a basic flow graphic visual representation. We can use Mermaid to export the Workflow domain to an SVG/PNG image representation
2. Improve the Java DSL by adding static imports shortcuts to the consumers. Instead of chaining consumers, users can also import static classes like io.serverlessworkflow.fluent.spec.DSL.* and have shortcuts, such as event(type("org.acme.reply")).
3. Improve documentation on the provided integration tests
4. Add more use cases as we see fit
5. Add Ollama to the optional integration test pipeline on PR checks to run the agentic use cases