Show total number of items in sync-tasks

[m-bucher]

Is your feature request related to a problem? Please describe.
pulp_deb progress_reports during sync tasks should show the total number of items to process. Currently it just says null:

"progress_reports": [
        {
            "code": "update.release_file",
            "done": 0,
            "message": "Update ReleaseFile units",
            "state": "running",
            "suffix": null,
            "total": null
        },
        {
            "code": "update.packageindex",
            "done": 10,
            "message": "Update PackageIndex units",
            "state": "running",
            "suffix": null,
            "total": null
        },
        {
            "code": "associating.content",
            "done": 544,
            "message": "Associating Content",
            "state": "running",
            "suffix": null,
            "total": null
        },
        {
            "code": "sync.downloading.artifacts",
            "done": 938,
            "message": "Downloading Artifacts",
            "state": "running",
            "suffix": null,
            "total": null
        }
    ]

Describe the solution you'd like
I reckon this could mean iterating over the PackageIndex before actually processing it, maybe a 'nicer' solution is possible.
Nevertheless, it would make the current state of the task more transparent.

[quba42]

Do other Pulp plugins implement this?

[mdellweg]

Maybe it is possible to keep the stream-processing, but set the value once the last PackageIndex has been fetched.
If we increased the total value for each item we put into the queue, it would probably be more confusing than helping.

[quba42]

OR-1242