Add support for Docker images (OCI Format)

[scovetta]

We should be able to extract from Docker images - either OSI-compatible or another format.

[gfs]

I did a bit of searching but I was not able to find a C# api for parsing OCI images.

I think the spec is open, if so and we considered it high priority I could implement a parser from the spec, like I did for .ar files (though I suspect the spec for OCI is more complex).

I did find that the Docker cli has a method to export an image as a tar file, if you want a workaround you can use right now.

https://docs.docker.com/engine/reference/commandline/image_save/

[gfs]

OCI image spec:

https://github.com/opencontainers/image-spec

[gfs]

The reference implementation is in go. One potential option is to start with a Go to C# converter like this one: https://go2cs.net/.