remove repo from FSISubsystem, use scope instead

[dustmop]

TODO from dispatch PR: https://github.com/qri-io/qri/pull/1653/files
// TODO(dustmop): This subsystem contains global data, we should move that data out and
// into scope [FSISubsystem uses Repo]

The FSISubsystem in fsi/fsi.go has a Repo that lib gives it as construction time. This
should be removed, and scope should instead be passing any necessary data structures down
to the FSISubsystem.