iSCSI configfile

Hello,

lio-t supports a config file. It would be very nice if you also support that like
`targetcli restoreconfig /etc/rtslib-fb-target/saveconfig`
If you create a iSCSI target first time its much easier imho to handle and you don't need to care about iSCSITarget and iSCSILogicalUnit and in which order etc.

Start by tracing how the repository currently creates iSCSI targets and how the targetcli restoreconfig command represents that setup. Compare the requested config-file workflow with the existing resource-agent behavior and identify the integration boundary. Done means a first-time iSCSI target can be configured from the requested file without manually ordering iSCSITarget and iSCSILogicalUnit resources.

Written by the indexing model from the issue text.