libdebugger: Minor fixes to NetworkTargetHostInterface classes.

NetworkTargetHostInterface:
- Fix missing initializer. This would lead to a crash in the destructor.

NetworkTargetHostInterfaceInfo:
- Implement IsConfigured() to validate passed in settings.

libdebugger: Add initial version of network interface.

NetworkTargetHostInterface{Info}:
- Barebones classes for implementing a target host interface over TCP.