feat(core): Workflow Execution Statistics (#4200)

Add recording and reporting of workflow execution statistics

packages/core/src/EventEmitter.ts

@@ -0,0 +1,15 @@
+import EventEmitter from 'events';
+
+interface EventTypes {
+	nodeFetchedData: string;
+	workflowExecutionCompleted: string;
+}
+
+class N8NEventEmitter extends EventEmitter {
+	types: EventTypes = {
+		nodeFetchedData: 'nodeFetchedData',
+		workflowExecutionCompleted: 'workflowExecutionCompleted',
+	};
+}
+
+export const eventEmitter = new N8NEventEmitter();