Deprecate Netconf Loopback Mount Through Config Subsystem

Deprecate the Netconf Loopback mounting mechanism (through config subsystem) in favor of CDS (spawning netconf connectors through topology configuration). The latter topic is discussed in detail here:

https://wiki.opendaylight.org/view/OpenDaylight_Controller:Config:Examples:Netconf#Spawning_netconf_connectors_via_topology_configuration

A description of Upgrade Considerations for existing data is here:

https://wiki.opendaylight.org/view/OpenDaylight_Controller:Config:Examples:Netconf#Upgrade_Considerations

The idea is that this enhancement bug requires replacement of missing mechanisms that are needed to successfully deprecate mount via config subsystem. Namely, this includes:
1) Providing a mechanism to automatically mount a device at controller startup.
2) Mounting the controller at startup.