The interfaces and their addresses are already available via
the stack Intefaces and InterfaceAddrs.
Also add some tests as we had no tests around SIOCGIFCONF. I also added the socket_netgofer lifecycle for IOCTL tests.
PiperOrigin-RevId: 201744863
Change-Id: Ie0a285a2a2f859fa0cafada13201d5941b95499a