Feature Request: add subinterface creation

/kind feature

**Description**

`docker network create` allows automated creation of trunk bridge mode vitual IPs that map to each created container if you call a new subinterface name, such as "eth0.2". This is useful for running services under podman that might normally get their own virtual IP, such as serving DNS.

It would be nice to have this option in podman as well, particularly for folks who are moving services from native executables to podman containers.

Realistically, it will take a significant amount of work to make this happen since CNI is more complicated than whatever docker is doing, but I wanted to get this in the queue in case someone was looking for networky things to hack on.

While you're implementing this, it would be nice to have podman support the `--parent` switch for syntax compatibility with docker network create

## References

* https://docs.docker.com/network/macvlan/
* https://github.com/containers/libpod/blob/master/docs/source/markdown/podman-network-create.1.md