Users should be able to explicitly set the author of a post.
Admins and editors may publish the work of other writers, and want to attribute it to someone else -- especially an outside contributor T734.
When publishing to a Organizations blog:
- Classic editor: add an "Authors" field in a modal that appears before publishing the post
- Users can choose 1 or more authors from an autocompleting dropdown
- Prevent publishing if no authors are selected (or attribute to user)
- Metadata editor: add an "Authors" field that allows users to change the author
- Accept an authors array of strings, each representing an author's slug
- Associate these authors with the post