Distributed and Inline BFD support for IPv6 link-local address

We support distribution of OSPFv3 and ISIS BFD sessions which use IPv6 link local address. To forward packets with link local ipv6 address as destination from microkernel, we provide next-hop id as part of the packet which the PFE uses to forward the packet on right interface. Also, we support inline mode and by default the IPv6 Link local BFD sessions will operate in inline mode. This feature is supported on MX Series MPCs 1 to 9. This is not supported on MX Series MPCs 10 and 11.