dir_data: beginning of a new struct for directories
dir_data: beginning of a new struct for directories

Issue: KBFS-3301

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