[Mainline] Copy the method getSelectableSubscriptionInfoList from SubscriptionManager to Settings

Bug: 147206736
Test: make RunSettingsRoboTests -j ROBOTEST_FILTER=SubscriptionUtilTest
      make RunSettingsRoboTests -j ROBOTEST_FILTER=MobileDataSliceTest

Change-Id: I6d7e72a656723c0620d579e1e223945e2a3588af
4 files changed