northd, lsp: Arp proxy additional features

[qinqon]

Add the following additional features to arp proxy:

• IPv6 support
• Fixed MAC
• cidr match

[qinqon]

The IPv6 neighbour solicitation is fine and the icmp destination mac is fine too but OVN is not answering to it

00:00:00.106114 f0:00:00:01:02:03 > 33:33:ff:00:00:01, ethertype IPv6 (0x86dd), length 86: (hlim 255, next-header ICMPv6 (58) payload length: 32) fd11::2 > ff02::1:ff00:1: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has fd7b:6b4d:7b25:d22f::1
	  source link-address option (1), length 8 (1): f0:00:00:01:02:03
	    0x0000:  f000 0001 0203
 00:00:00.000564 0a:58:a9:fe:01:01 > f0:00:00:01:02:03, ethertype IPv6 (0x86dd), length 86: (hlim 255, next-header ICMPv6 (58) payload length: 32) fd7b:6b4d:7b25:d22f::1 > fd11::2: [icmp6 sum ok] ICMP6, neighbor advertisement, length 32, tgt is fd7b:6b4d:7b25:d22f::1, Flags [router, solicited, override]
	  destination link-address option (2), length 8 (1): 0a:58:a9:fe:01:01
	    0x0000:  0a58 a9fe 0101
 00:00:00.000009 f0:00:00:01:02:03 > 0a:58:a9:fe:01:01, ethertype IPv6 (0x86dd), length 118: (flowlabel 0x0d8dd, hlim 64, next-header ICMPv6 (58) payload length: 64) fd11::2 > fd12::2: [icmp6 sum ok] ICMP6, echo request, id 3072, seq 1
 00:00:00.299817 f0:00:00:01:02:03 > 0a:58:a9:fe:01:01, ethertype IPv6 (0x86dd), length 118: (flowlabel 0x0d8dd, hlim 64, next-header ICMPv6 (58) payload length: 64) fd11::2 > fd12::2: [icmp6 sum ok] ICMP6, echo request, id 3072, seq 2

[almusil]

Hi,
there are some questions about the approach and small issue with memory management, but other than that it looks good. Thanks!

[almusil]

Nice, it looks better a few additional things.