This is faster than going back to nextcloud to download the files.
This is an opt-in setting that can be enabled by setting
use_presigned_url in the object store config.
Additionally add support for the proxy config which is needed in a
docker setup. See https://github.com/juliusknorr/nextcloud-docker-dev/pull/431
Signed-off-by: Carl Schwan <carl.schwan@nextcloud.com>