Merge changes I13495cad,I3a44c4c4,I15bff230,I8a492866,Ia7ffe34a

* changes:
  [Pair hearing devices] Add pair hearing device functionality
  [Pair hearing devices] Extract common behavior in BluetoothPairingDetail into Base class
  [Pair hearing devices] Add "Hearing devices" to show connected hearing devices
  [Pair hearing devices] Add "Saved devices" to show bonded but not connected hearing devices
  [Audio routing] Setup basic structure for audio routing page