Add list of selected/excluded convos to bubble settings

* Some changes to extend AppConversationListPrefController
* When a user removes something from the selected or
  excluded list that resets the channel setting

Bug: 148619540
Test: make -j40 RunSettingsRoboTests ROBOTEST_FILTER="Bubble"
Change-Id: I7a9ed7b70208dbdefca6c3c09d34d55c65f06408