Add local interconnect data to DeviceLocality.

This information can be used within a distributed implementation
when deciding how to route data transfers that might involve more
than one hop.  By default the new fields are populated according to
StreamExecutor::CanEnablePeerAccessTo(), however a platform-specific
implementation can augment them with more detailed values.

Do some refactoring of gpu_device and gpu_device_factory, making
GetDeviceLocalities() and GetInterconnectMaps() into virtual
functions.

PiperOrigin-RevId: 184698821