Rework document L3 authors

[mhaack]

Usage of Authors & Display Authors must be cleaned up.

• [x] update import for News
• [x] update import for Insights
• [ ] only use Authors, can be single or list
• [x] only index Authors
• [x] display all authors first author on L3 Hero
• [x] display all authors in author profile block
• [ ] content-list cards display only first author

[pahupe]

Note: Blocks should now use article.js: getAuthorNames to fetch author names