[Feature Request] Add multiple additional users to sync watched status (aka "Permanent Users")

[g0tmk]

Jellyfin for Kodi supports a setting called "Permanent Users" - this allows you to add additional users in the settings so that when something is watched, the watched status updates on multiple users at once.

Swiftfin has completely replaced my need for Kodi these days, this is the only feature that I really miss from the old setup.