Goal:

• Show progress information during the bootc-image-builder runs.
• An image build can take some time, easily 10-30min. Right now the progress is either invisible or full of debug output. In both cases no progress bar or othe information is visible that indicates at what step of the journey the build is.
• In addition to a nice human visible progress we should also support structured json output to accomodate frontends (like a potential GUI on top of podman-desktop or the web-frontend).

Acceptance Criteria:

• A build has a clean progress bar with overall sources/pipeline progress and subprogress for the individual pipeline stages.
• A json based progress mode should be available as well.
• Bonus points (maybe a separate epic?) if the individual stages can report progress. This is useful because e.g. the curl source download can take a long time for an empty cache. Also the rpm stage tends to dominate the overall progress but inside there is no machine readable subprogress transmited back to image-builder.

Open questions:

• Should we target progress from inside stages already or do this later? It will be hard for e.g. rpm as we just pass a long list of rpms to the rpm tool and then let rpm do things (which AIUI will not display progress information)