Implement `beforeAgentInvocation` and `afterAgentInvocation` for LC4J 1.6.0

[ricardozanini]

What would you like to be added:
After upgrading to LC4J 1.6.0 our implementation of their workflow API is missing the handlers for before and after agent invocation.

This can be mapped to our inputFrom (before) and outputAs after for each call agent task.

There are new objects introduced by the API named AgentRequest and AgentReponse that carry the input and output, respectively, to the calls that we must handle with AgenticScope.

Why is this needed:
To be 100% compatible with their API.

As a workaround, one can use our DSL instead and have more control of each agent call by implementing their own Function on inputFrom and outputAs. For example:

AgentWorkflowBuilder.workflow().tasks(t -> t.agent(agent).inputFrom(AgenticScope -> {}).outputAs(AgenticScope -> {}))

And infer directly into the input/output of the agent task. Simple.