feat(chat): add support for chat part messages. Closes #3201 (#3291)

core/chat/events/userPartEvent.go

@@ -0,0 +1,17 @@
+package events
+
+// UserPartEvent is the event fired when a user leaves chat.
+type UserPartEvent struct {
+	Event
+	UserEvent
+}
+
+// GetBroadcastPayload will return the object to send to all chat users.
+func (e *UserPartEvent) GetBroadcastPayload() EventPayload {
+	return EventPayload{
+		"type":      UserParted,
+		"id":        e.ID,
+		"timestamp": e.Timestamp,
+		"user":      e.User,
+	}
+}