The RHEL 7 vpc subformat in qemu does not support force_size so we need
to be able to disable it. The parameter in all parts is defined as a
pointer because the default value is 'true'. Not specifying it will
keep the option in the osbuild stage as 'nil', falling back to 'true' in
osbuild.
For now this encapsulates osbuild export and filename in that
exported tree. In the future we could add MIME type.
For now this is a concrete type, but should probably be an
interface, so the consumer of artefacts know they are the right
type. Enforcing we only push AMIs to EC2, etc.
Similarly to how checkpoints work, each pipeline can be marked for
export, and the manifest can return all the names of the exported
pipelines, to be passed to osbuild. Additionally, the Export
function returns an artefact object, which can be used to know how
to access the exports once osbuild is done. For now, this is unused.
We have three kinds of operating system trees, until we unify them to one,
hide them behind one interface. Use this to read the architecture from the
Tree rather than pass it in as a string to parent pipelines.
Also, make the filename parameter optional in a few places, there should be no
reason to set this rather than introspect it (except for backwards
compatibility).
Lastly, add another playground example sample to build a raw image.
For now all it does is represent the name of the runner and what requirements
it has of the build pipeline.
Move some package definitions from the runner package set to where it belongs.
A build pipeline now tracks all its dependents, and each pipeline
now implements a `getBuildPackages()` method. For now those
return the empty slice, but will be extended by each pipeline in the
future.
`getPackageSetChain() of the build pipeline simply collects all the
build package sets of its dependents.
Make it the responsibility of each pipeline to track its required
sources, and use this to generate a manifest from its pipelines.
This removes the dependency on osbuild2 from distro.go, and the
only other uses of osbuild2 are to specify parameters in
ImageConfig, which will eventually go away too.
As a consequence, this only attaches the required sources for a
given manifest, rather than all known packages in the package set
map.
