CLSA-2025-1762420748 frr: Fix of 4 CVEs

CVE-2023-41358: fix crash when processing NLRIs with zero attribute length - CVE-2023-47235: fix EOR handling to avoid unwanted processing of malformed attributes - CVE-2023-46753: fix mandatory attributes check for UPDATE messages with unknown transit attributes - CVE-2023-47234: fix handling...