exclude static route with via ip in route helper

[zwf]

When adding some routes to zerotier's managed routes, the helper script will add a route rule without via ip to the container's ip route, so the address of the destination ip segment cannot be routed correctly within the container.
Here, based on the contents of the routes key in json of
zerotier-cli -j listnetworks, by determining whether the via key has an ip address, if it is not null, helper will no longer add this route rule.

for example:

• suppose our managed routes in my.zerotier.com like this: 10.10.0.0/16 via 172.23.0.1 and a LAN 172.23.0.0/16.
• the Route Helper script will add two routes in container like this:

  172.23.0.0/16 dev $IFNAME scope link
  10.10.0.0/16 dev $IFNAME scope link
  

• but the right route should be like this:

  172.23.0.0/16 dev $IFNAME scope link
  10.10.0.0/16 via 172.23.0.1 dev $IFNAME metric 5000 //should be added by zerotier automaticlly
  

[joseph-henry]

This is great. I appreciate you fixing this.