cr_actions: track unrefs for unmerged sync ops on new files
cr_actions: track unrefs for unmerged sync ops on new files

Also, factor the ref/unref logic into its own function for clarity.

Issue: KBFS-1193

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