Extend netconf-node-topology model to distinguish user overriden capabilities from device reported capabilities

Netconf-node-topology model currently does not distinguish between capabilities overrided by user (https://wiki.opendaylight.org/view/OpenDaylight_Controller:Config:Examples:Netconf#Connecting_to_a_device_not_supporting_netconf_monitoring) and device provided capabilities (reported in netconf monitoring and in netconf hello message). Both are listed just as available-capabilities.

It would be better to see the difference.