Populates @microsoft.graph.downloadUrl on file driveItems when requested
via $select and implements GET .../items/{item-id}/content as a 302 to
the same URL: a by-id WebDAV URL signed with OC_URL_SIGNING_SECRET,
verified by the proxy, valid for 30 minutes. Folders answer 404 on
/content and never carry the annotation.
The annotation is available on the driveItem stat, the children and
root children listings and the share jail item endpoint.
Dominik Schmidt
5807eea186