cli: Use temporary scheduler as fallback when no configuration detected
In order to simplify the testing of listers, allow to call the run command
of swh-lister
CLI without scheduler configuration. In that case a temporary
scheduler instance with a postgresql backend is created and used.
It enables to easily test a lister with the following command:
$ swh -l DEBUG lister run <lister_name> url=<forge_url>
Used by swh-scheduler!349 (merged)
Edited by vlorentz