Have MultiSimSettingController listen to carrier config changes

When SIM is added or swapped, have MultiSimSettingController wait until
carrier config is loaded before evaluating whether to pop up SIM related
dialogs or disable grouped oppotunistic subscriptions. Because carrier
config may update opportunistic bit and groupUuid.

Bug: 136187220
Test: manual and unittest
Change-Id: Ife069855f1366c68e6359f7ecdcd92991546cf99