Add test coverage for requests of a single user resource for authors of post types registered as: - public = true, show_in_rest = true: success without auth. - public = true, show_in_rest = false: fail without auth. - public = false, show_in_rest = true: success without auth. - public = false, show_in_rest = false: fail without auth. See #38878. Fixes #39546. git-svn-id: https://develop.svn.wordpress.org/trunk@39913 602fd350-edb4-49c9-b593-d223f7449a82