Clarify what "shared" means. Always return owner name. New flag for self-ownership. Remove isLinked.
- "Shared" means a notebook that users besides you have access to. For a personal notebook, this can be a notebook
   you created and shared with others, or a notebook that someone else created and shared with you. For a
   business notebook, this can be a notebook you created and invited specific people to, or published to the whole
   business, or someone else's notebook that you joined. All of these are "shared". Note that business notebooks
   that are not shared are still "visible" to the business admin, not private in the sense of personal notebooks.
- ownerName => ownerDisplayName. Always returns a valid string with our best version of the owner's display name.
  For use in UI, not guaranteed unique.
- isOwnedByUser flag. Returns YES for all personal notebooks that are yours, and all business notebooks for which
  you are the contact.
- isLinked is now private; this has a specific semantic around the EDAM model that is useful internally to the SDK
  but probably not useful for holders of ENNotebook objects.