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
9ab540719e