Title is now owned by document_versions, following the same pattern as
classification and document_type. The documents.title column is made
nullable with a TODO to drop it. Backend loads title from a
latest_versions CTE for ordering purposes only. The frontend resolves
title from the latest version, and DocumentTitleForm now operates on
DocumentVersion using UpdateDocumentVersion mutation.
Signed-off-by: Sacha Al Himdani <sacha@getprobo.com>
b63f043849