Windows Containers Support

I'm trying to prototype using crank in DnD (Docker-in-docker) so I'm abusing the the docker hostname argument on the agent and the arguments job property.

That said, all these problems should occur outside of the container as well:

Windows containers docker commands are generated by:
https://github.com/dotnet/crank/blob/ea81a866146a5733eba9aac74c79afd66cb8efd6/src/Microsoft.Crank.Agent/Startup.cs#L1911

Where hostname is the value of the OS's hostname or the value passed form `--docker-hostname`. That means the `--ip` is set to a hostname, which is invalid (must be an IP).

```
[STDERR] docker: Error response from daemon: invalid IPv4 address: 13ad8aac2fae
```

If `--docker-hostname` is set to an IP e.g. `--docker-hostname 172.21.154.177`, the run command fails further with:

```
[STDERR] docker: Error response from daemon: network SELF not found.
```

I'm unsure where the `SELF` network comes from, I don't think it's a built in network.

---------

Completely unrelated, true DnD support would be amazing, would this project be open to supporting that? I can make the required changes (resolve an IP from the constructed container and use that in-place of the docker hostname, could be an opt-in flag).