[WLANCONF] Fix getting the interface GUID value

[WLANCONF] Fix getting the interface GUID value

GetInterfaceInfo returns interface name in Windows XP and 2003
in this format: `\DEVICE\TCPIP_{GUID}`.

MSDN says that the `Name` member of the `IP_ADAPTER_INDEX_MAP`
may start with '{' character on Windows Vista and later.
https://docs.microsoft.com/en-us/windows/win32/api/ipexport/ns-ipexport-ip_adapter_index_map

Change the code to support both cases. CORE-18032