Add `extra-tags` parameter to `ods-package-image` task

[michaelsauter]

It would be handy if one could specify one (or multiple?) additional tags as a parameter to ods-package-image. This would allow, for example, to tag an image not just with the Git commit SHA, but also with latest or something like that.

FYI @henrjk based on our discussion this week

[henrjk]

I think you meant to say additional tags as a parameter

I can volunteer to work on this.

[michaelsauter]

Good catch, corrected!