cli.add_forge_now: Open register-lister with sensible defaults
This will ease scheduling of new add-forge-now requests, on:
- staging: this will list a subset of disabled origins once
- production: this will register recurring tasks (full, incremental if any) to list that new forge
This also unifies the previous subcommand schedule-first-visits with the --preset flag.
So, the following would be enough to list appropriately in staging/production:
swh scheduler add-forge-now \ ( --preset [production|staging] \ # to enable a pre-defined set of rules ) register-lister \ gitea \ url=https://git.afpy.org/api/v1/
Related to https://gitlab.softwareheritage.org/infra/sysadm-environment/-/issues/4674