Add a blog visibility setting that makes the blog and all posts available only to other registered users on the instance.
It should be possible to run an instance in an internal environment, where writing is only shared with other registered users.
This should be a new instance-level configuration setting, something like internal_only. If it's true, blogs and their pages should only show content when requester is authenticated as a user (owner or not) on the instance. If not authenticated, these pages will always return a 404.
This setting should be checked:
- On the web
- Via the API
Also when true:
- Posts should never federate
- Public stats should never show