simplefs: filter out errors when public TLF is empty
simplefs: filter out errors when public TLF is empty

When you don't have permission to create a public TLF, we want to show
it as empty, and SimpleFS was missing a few of those cases.

Issue: HOTPOT-666

keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client