netifd: Route traffic from LAN to WAN using rules

netifd: Route traffic from LAN to WAN using rules

After commit ebd3d8417c7a ("interface: fix moving interface address routes to
the table specified by ip[46]table"), it is no longer possible for clients on
LAN to reach machines on the WAN.

This patch restores support for clients on LAN reaching clients on WAN by using
rules. The rules are placed after the address rules, in order to make sure that
traffic originating from the router is routed correctly.

Signed-off-by: Kristian Evensen <kristian.evensen@gmail.com>