Add suppliers and shortcuts for the Agentic DSL

**What would you like to be added**:

Having done #730 for the base spec, now we can start adding the suppliers, consumers, and DSL recipes to the agentic DSL too. As a reference for the DSL, we can use LangChain4j `agentic` module.

**Why is this needed**:

The reason is similar to the original issue, but now pursuing the agentic use cases.