Queue the document for archival. The document — together with its
extraction results, review history, and the project configuration that
produced them — is copied into a new project with archived status, and
is then removed from this project. Archival runs in the background and
waits for any active processing on the project to finish first; until
it completes, the document remains listed with archive_requested_at
set. Only available for projects in per-document mode.