Split branch settings LMS 2916

https://edx-wiki.atlassian.net/browse/LMS-2916
If we need temporary compatibility w/ existing Studio gui w/ explicit convert to draft gesture, then this should be:
```
  if xblock.location.category in DIRECT_ONLY:
      return PublishState.public
  else:
      return PubishState.draft  # temporary hack to make split based items always appear to be in draft
```