feat: add source/news authors management

[zefr0x]

Initial Idea

• Multiple authors can be associated with news sources or news items.
  • News item's author list dominate.
• An author is identified by (and/or)
  • URI
  • email
  • name (not required to be unique).
• An author may have
  • Large image
  • Small logo/icon
• Users should be able to overwrite authors' information for presentation purposes.
• Users may be able to manually create custom authors.
• Users may link an author manually to a source or overwrite an existing link.
• Users should be able to associate cryptographic keys for news author verification (either provide a generic handler or offload it to the informant implementation).