Enable custom byline or "display author" for news/blog posts

[pgoussy]

Is your feature request related to a problem? Please describe.
Similar to issue #2381 - one of our journals would like to feature a "Letters" section, where they can add letters that have been sent in by users. Again, a blog-like tool would work well here, if we could rename "News" to "Letters". In this case, we would also need to customize the byline for each letter to reflect the name of the reader who sent it in, rather than the editor who actually created the post.

This would also be convenient in situations where an editor creates a news post, but wants the byline to just display a generic name like "[Journal] Editorial Staff". (I recently created a few news posts while setting up a journal's homepage, and had to create a separate dummy account named "TIA Editorial Team" and manually reassign that account as the creator via the admin tool.)

Describe the solution you'd like
Ideally, the default byline would continue to display the name of the user who created the post, but there would also be an optional "Display Author" text field that would override the automated display.