Make boxkit an action

[castrojo]

Idea: Putting this in here instead of the boxkit repo because these would be the base images we use:

One of the reasons I made boxkit was so that I could take a good base toolbox from ublue-os and then add my favorite packages.

For the quadlet managed distroboxes we want to destroy and recreate the container regularly. There's an open issue for implementing keeping container state local.

But the more I think about I also don't want to manage a distrobox.ini on each machine either. So what if there was a boxgit github action that was just a packages.ubuntu list. One file, one github action, that'd be your whole personal setup, easy to fork-and-go. Then, as an example, my castrojo/bluefin-cli container will be ublue-os/bluefin-cli+ my packages.

And then boxkit itself will handle the customizers.

Then the scope of this repo starts to become clearer, we need good base images with recommended common tools but keeping it focused so that the strong opinion is controlled by the user.