Debian: Add SystemD template units for UNIX socket instances

debian/uffd-ldapd@.service

+[Unit]
+Description=Proxy server to provide uffd user and group data via LDAP
+After=network.target
+BindsTo=uffd-ldapd@%I.socket
+
+[Service]
+ExecStart=/usr/sbin/uffd-ldapd --socket-fd 3
+
+Restart=always
+RestartSec=10
+StandardOutput=journal
+StandardError=journal
+SyslogIdentifier=uffd-ldapd
+
+DynamicUser=true
+PrivateUsers=true
+CapabilityBoundingSet=
+NoNewPrivileges=true
+RemoveIPC=true
+LockPersonality=true
+ProtectControlGroups=true
+ProtectKernelTunables=true
+ProtectKernelModules=true
+ProtectKernelLogs=true
+ProtectClock=true
+ProtectHostname=true
+ProtectProc=noaccess
+RestrictRealtime=true
+RestrictSUIDSGID=true
+RestrictNamespaces=true
+RestrictAddressFamilies=AF_UNIX AF_INET AF_INET6
+ProtectSystem=strict
+ProtectHome=true
+PrivateTmp=true
+PrivateDevices=true
+SystemCallArchitectures=native
+SystemCallFilter=@system-service
+
+EnvironmentFile=/etc/uffd-ldapd-%I.conf
+
+[Install]
+WantedBy=default.target

debian/uffd-ldapd@.socket

+[Unit]
+Description=Proxy server to provide uffd user and group data via LDAP
+
+[Socket]
+ListenStream=/var/run/uffd-ldapd-%I.sock
+
+[Install]
+WantedBy=sockets.target