Improve orchestration by supporting event listeners #97
Description
Right now orchestrators are called each time a new utterance is given to the agent, this is a special case of one event: "new turn" / "new input" / "new utterance" event.
SDialog should allow other types of events to trigger orchestration, for instance, new tool call / tool response event. This, could allow for instance, allow to orchestrate the agent based on the tools called or tools responses (.e.g documents retrieved by RAG tool).
Simple example, have an orchestrator to check when documents are retreived (RAG tool call response), if retrieved documents not relevant to the context, change the query and call tool agent, etc.