feat!: Upgrade and Rebase commands

This add the new rebase and upgrade commands:

bb rebase config/recipe.yml

bb upgrade config/recipe.yml

The rebase command will clear out your current image archives and build a new one. It will then call rpm-ostree rebase ostree-unverified-image:oci-archive:/path/to/image.tar.gz. If the image baseref is the same, it will fail.

The upgrade command will build a new image file and run the rpm-ostree upgrade command on it.

The --reboot/-r option allows you to immediately reboot when the upgrade/rebase is done.