Read CarrierConfig to get operator name

Config if operator name should be in status bar is now read
from carrier config. For dual sim devices we use data sim.

Bug: 116847905
Test: Add item for carrier in vendor.xml and swap sim cards
between ones that have the item enabled and disabled. We have
also tested to swap data sim cards on dual sim device.
Test: m RunSettingsRoboTests ROBOTEST_FILTER="ShowOperatorNamePreferenceControllerTest"

Change-Id: I03311b96ee660aed80ec867b05aa0a34cfc15f54