DO NOT MERGE - Set country code even when device is not registered on network

Extends the functionality of getNetworkCountryIso to support
no SIM/no service case. When no SIM/no service, it returns
the country code of nearby network (unregistered but cell info
is available to the device).

Test: Manual
Bug: 64335394
Change-Id: Ic7c9e903cc497b7e43b557cb593407ff3e9305b5