Add Dockerisation and Collabora-specific patches

This does not include SSO yet.

Task: https://phabricator.apertis.org/T8044

docker/backend-docker-entrypoint.sh

@@ -12,6 +12,16 @@ then
     chown obsrun:obsrun -R /srv/obs
 fi
 
+if [ ! -d /srv/obs/gnupg ]
+then
+    echo "GnuPG homedir is missing!"
+    mkdir -m 0700 /srv/obs/gnupg
+    chown obsrun:obsrun /srv/obs/gnupg
+    gpg --list-keys --homedir /srv/obs/gnupg
+fi
+
+export GNUGPHOME=/srv/obs/gnupg
+
 if [ ! -f /etc/obs/BSConfig.pm ]
 then
     echo "OBS backend configuration not found, starting from scratch"