Add support to assign multiple static ip addresses to a docker container

[meyay (Metin Y.)]

@brookbot

I think real world systems with multiple interfaces are common and would share the file system as well as apps

A container by itself has no network interface as all. Try: docker run -ti --rm --network=none alpine ip a

A container gets a network interface per attached network, with an ip from the subnet of the network. If you are fine with ips from different subnets, then the solution is already there and simple to configure.