Extract duplicate part for hearing audio routing into SettingsLib

Similar functions need to be called when hearing device get connected, so move them into SettingsLib.

Bug: 269122580
Test: make RunSettingsRoboTests ROBOTEST_FILTER=HearingDeviceAudioRoutingBasePreferenceControllerTest
Change-Id: I15296fb81726c96c1d2fec7397e981e71e305450
6 files changed