Change log for PAN_FIREWALL

Date Changes
2022-03-28 Enhancement-Added mappings for certain fields when log is of type TRAFFIC/THREAT.
- Sequence Number to event.idm.read_only_udm.metadata.product_log_id.
- Session End Reason to event.idm.read_only_udm.security_result.summary.
- Session ID to event.idm.read_only_udm.network.session_id.