[Feature Request] Add OIDC back-channel logout option

Description


Paperless-ngx can redirect users to the identity provider when they sign out of Paperless. In my setup, this also signs them out of it.
The reverse does not happen: signing out from the identity provider leaves the existing Paperless session active.
Could Paperless-ngx optionally support OIDC back-channel logout? The identity provider would send a signed logout notification to Paperless, which would invalidate the corresponding Paperless session. Making this optional would preserve the current behavior for installations that do not need it.

I think it would be something nice to implement, as it makes sense with SSO. Though it should be an option, like it is with Immich or Opencloud.