WIP: Add cosa import

[jlebon]

This command takes as argument a containers-transport(5)-style pullspec and creates a new cosa build dir from it. It essentially bridges the gap between coreos/fedora-coreos-config#3348 and the rest of the cosa pipeline.

[openshift-ci]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[jlebon]

Emphasizing the "WIP" part here. This is not complete, but hopefully is enough scaffolding to see how I've been thinking about this.

The end goal should be that you can then cosa list and it shows up, cosa buildextend-qemu, etc...

[jlebon]

For the meta.json piece, the goal shouldn't be that we re-implement every piece of metadata in meta.json, but rather just the ones that are relevant for the new container flow (and possibly add new fields if needed) and then we adapt consumers of that metadata as needed to support that.

[jbtrystram]

cc @jcapiitao we will want this for konflux tests

[joelcapitao]

cc @jcapiitao we will want this for konflux tests

yup, I'm waiting for this feature to unblock https://issues.redhat.com/browse/COS-3327
The Konflux trigger-jenkins-job is ready, so now the next step is to be able to consume the Konflux artifact with cosa import.

[jlebon]

Closing in favour of #4164.