Look for private status posts if editor or admin

[oscarssanchez]

Description of the Change

Hi @tlovett1 ,

Could you please review this PR which addresses #1800?

This changes the is_user_logged_in() check in favor of checking if the current user is either an editor or an administrator, and displays private posts only to them. Both in the frontend and in the admin.

As per WP documentation, private posts should only be visible to editors and administrators: https://developer.wordpress.org/reference/classes/wp_query/#status-parameters and without Elasticpress enabled, I could confirm this was true.

Additionally, the PR solves another bug I spotted, which lets authors and contributors see just anyone private posts in the admin if Elasticpress is enabled.

Alternate Designs

Benefits

Not allowed users won't see post they should not. Allowed users should be able to see private posts in the frontend.

Possible Drawbacks

Verification Process

• Create a private post.
• Index with Elasticpress.
• Query in the frontend as an editor/admin and see private post.
• Query in the backend as an author/contributor and no private post is returned.

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests passed.

Applicable Issues

Changelog Entry

[oscarssanchez]

Also confirmed it fixes #1870