feat(core): support flowtables, [sd]nat, th match

[TkPegatron]

Added highlight support for matching transport headers, creating flowtables, and performing NAT

Example code:

table inet filter {
  flowtable f {
    hook ingress priority 0; devices = { wan, lan, iot, manage };
  }
  chain forward-chain {
    type filter hook forward priority 0; policy drop;
    meta l4proto { tcp, udp } flow offload @f
  }
}
table inet nat {
  chain nat-prerouting {
    type nat hook prerouting priority -100;
    iifname {
      "lan", "iot", "wgra0", "management" 
    } meta l4proto { tcp, udp } th dport 53 dnat ip to 172.22.0.1
  }
}

[omBratteng]

Thanks for the PR, I will take a look at it shortly.

[omBratteng]

@all-contributors please add @TkPegatron for code

[allcontributors]

@omBratteng

I've put up a pull request to add @TkPegatron! 🎉