Google Code-in

This task is about the Newsletter extension

Currently the UI for adding and removing publishers consists of a textarea where usernames of publishers have to be typed in new lines, and they all can be remove with a single selectAll - delete - save. Not very elegant.

Instead, it could be something different, and something like adding in tags as in https://phabricator.wikimedia.org/T131492#2904672

Even better if new publishers would be added using autocomplete, just like we do with Main Page Title in Create Newsletter.

Warning: Please read https://phabricator.wikimedia.org/T131492#2904672 before you claim this task! We can add in more time, no issues!