bootc isn't in C9S yet, but it is in the -dev images. Add
the install config unconditionally so that `bootc install`
works in the `centos-bootc-dev` image.
This is basically just:
- kernel
- systemd
- selinux-policy-targeted
- bootc
Notably it doesn't have `rpm-ostree` or `rpm`, or many other things.
It also doesn't even have `linux-firmware`.
And no `openssh`!
It's almost certain that you need to derive from this, but
it should be a suitable starting point.
TODO: Add something like
```
$ dnf-system-bootstrap
Installing packaging tools from quay.io/fedora/fedora-boot-dnf@sha256:abcd...)
# This would be basically all the packages not in tier-0 that
# are enough to give `dnf install`
$ dnf install cowsay
# Install critical stuff
$ dnf system-bootstrap remove
# Remove everything that we added for the package system, that isn't
# a dependency of what the user wants!
```
(In theory we could make this work with multi-stage builds, but
it's a little hard)
Colin Walters