Build Graal native images in a docker container

[jroper]

This has been talked about a little in #1165, I'm creating an independent issue for it.

The big reason for building native images in a docker container is that Graal native images don't support cross compiling to different platforms from the host, so the native image you build will be specific for your platform. ie, if you have a Mac, and you build a native image there, you won't be able to deploy that image to Linux.

@adamw has a great blog post on building Graal native images in a docker container with sbt here, as a starting point.

In #1165, a good point is made that building in a docker container would be also useful for building debs and rpms, and so the feature should hopefully be somewhat reusable. That said, I'm not sure how much reuse there is to be had. The docker containers required to do the build are completely different, for Graal, you need one with Graal native-image installed. For debs, you need a Debian based distro image, and for rpms you need a RedHat based distro image. Furthermore, what needs to actually be done in those containers varies wildly depending on the task. For Graal, it's just a matter of running the container with a few directories mounted and passing a few arguments. For rpm/deb I would imagine it would first require installing a bunch of dependencies etc. I wouldn't be surprised if the only thing that makes sense to share between them is the location of the docker executable, from that point on, each build is going to do very different things with very different docker containers, I'd be surprised if there's anything else that could be shared.

So I think the best approach is to implement them independently, and then if any common functionality is discovered, we can refactor them to share it, but I don't expect that any will be.

[jroper]

Implemented in #1251.