Bluetooth: DUN: Add framework changes to support DUN

Bluetooth DUN profile APIs added to the framework APIs.
As DUN server supports only disconnection of DUN profile
level connection this API is implemeted along with other
APIs.

It registers bluetooth state changed callback with the
adapter service,once there is a change in the bluetooth
state,it will bind/unbind the DUN service which is
implemented in BluetoothExt.APK.

DUN service, and other DUN Application layer are mplemented
in BluetoothExt.APK.

Change-Id: I6ce1204ac6138e28ad7486f2855f0f7444ad3886

Change-Id: I6ce1204ac6138e28ad7486f2855f0f7444ad3886