Refactor itemid -> identifier

[mitra42]

• [ ] deal with stuff already on disks - minimal so maybe easiest to redo
• [ ] fork each repo and check
• [ ] dweb-archivecontroller
  • [ ] handle read from protocol - convert to identifier
• [ ] dweb-archive
• [ ] dweb-mirror
  • [ ] AIP should convert from itemid to identifier if not found
• [ ] dweb-metadata
• [ ] dweb-torrent