Lister schema: add is_fork and forked_from_url fields
This expands the schema to add fork (boolean yes/no/unknown) and fork source (URL field) if available from the listers, which will be usable for scheduling heuristics (e.g. for GitHub).
This expands the schema to add fork (boolean yes/no/unknown) and fork source (URL field) if available from the listers, which will be usable for scheduling heuristics (e.g. for GitHub).