Add source to LLM Guardrail events (#3572)

This commit adds the source attribute to LLM Guardrail event calls to
identify the Lite Agent or Task that executed the guardrail.

Author: vinibrsl

src/crewai/lite_agent.py

@@ -367,6 +367,7 @@ def _execute_core(self, agent_info: dict[str, Any]) -> LiteAgentOutput:
                 output=output,
                 guardrail=self._guardrail,
                 retry_count=self._guardrail_retry_count,
+                event_source=self,
             )
 
             if not guardrail_result.success: