Proxy ARP/NDP suppression with and without IRB

This feature adds support for proxy ARP and proxy NDP with ARP/NDP suppression in EVPN-MPLS (MAC-VRF) deployments with or without integrated routing and bridging (IRB). In deployments with IRB, the local PE router with IRB responds to ARP and NDP requests using MAC-IP information in the EVPN database. In deployments without IRB, the local PE router provides the same proxy and suppression behavior without requiring IRB configuration. By responding locally instead of flooding ARP and NDP requests through the EVPN domain, this feature reduces unnecessary control traffic and improves core bandwidth efficiency. Proxy ARP, ARP suppression, proxy NDP, and NDP suppression are enabled by default.