extensions: libxt_devgroup: Add translation to nft

extensions: libxt_devgroup: Add translation to nft

Add translation for device group to nftables.

Examples:

$ sudo iptables-translate -A FORWARD -m devgroup --src-group 0x2 -j ACCEPT
nft add rule ip filter FORWARD iifgroup 0x2 counter accept

$ sudo iptables-translate -A FORWARD -m devgroup --dst-group 0xc/0xc -j ACCEPT
nft add rule ip filter FORWARD oifgroup and 0xc == 0xc counter accept

$ sudo iptables-translate -t mangle -A PREROUTING -p tcp --dport 46000 -m devgroup --src-group 23 -j ACCEPT
nft add rule ip mangle PREROUTING tcp dport 46000 iifgroup 0x17 counter accept

$ sudo iptables-translate -A FORWARD -m devgroup ! --dst-group 0xc/0xc -j ACCEPT
nft add rule ip filter FORWARD oifgroup and 0xc != 0xc counter accept

$ sudo iptables-translate -A FORWARD -m devgroup ! --src-group 0x2 -j ACCEPT
nft add rule ip filter FORWARD iifgroup != 0x2 counter accept

Signed-off-by : Shivani Bhardwaj <shivanib134@gmail.com>

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>