gitea_fork can only express the source repo and owning organisation, so any
other setting in a fork's yaml is silently dropped.
- validate fork_from entries carry no other repository attributes, naming the
offending config key and attributes
- note that gitea_fork has no archive_on_destroy
Express a fork as an optional fork_from key on the repository yaml, so a
forked repo is declared the same way as any other repo.
- add fork_from "<owner>/<repo>" to the repository module and object type
- create gitea_fork instead of gitea_repository when fork_from is set
- validate the source repo name matches the config file name, since a fork
inherits the source name
- move gitea_repository.this to index 0 for the count refactor
- index existing repository import targets to match
unkin-agent