cli: Change default program behavior to iterate over all projects

Add `promote_project_release()` to promote releases of projects
generically. If no `release_version` is provided, user input is
requested to select a release that is not yet promoted.
Change `main()` to rely on `promote_project_release()` by either
promoting a specific release of a project (if the project or the project
and the release version are provided) or iterating over all available
projects in the configuration to allow the user to promote releases for
3 jobs for issues/5 in 54 seconds (queued for 9 seconds)