JET: Dynamic next-hop interface binding

Programmed RIB routes react to Up, Down, Add, and Delete events for direct next-hop interfaces. When all direct next-hop interfaces are unusable, the route becomes inactive. This prevents traffic from being dropped and keeps inactive routes from being propagated through the network. This feature applies to all routes programmed using the rib_service JET API where an interface is configured as a direct next hop, including interfaces that are part of a flexible tunnel. It also applies to tunnels configured with the flexible_tunnel_service JET API. To disable this feature, use edit routing-options programmable-rpd rib-service dynamic-next-hop-interface disable.