Editor: Show 'View Post' for any post the author can read.

This expands it to private posts and matches the logic in the toolbar.

props mordauk, SergeyBiryukov.
fixes #27059.


git-svn-id: https://develop.svn.wordpress.org/trunk@27483 602fd350-edb4-49c9-b593-d223f7449a82