Add new API for notifying volume changed on absolute device

Previously the client would call set/adjustStreamVolume with
FLAG_ABSOLUTE_VOLUE/FLAG_BLUETOOTH_ABS_VOLUME. This is replaced with the
AudioDeviceVolumeManager#notifyAbsoluteVolumeChanged method.

Test: atest AudioDeviceVolumeManagerTest
Flag: android.media.audio.unify_absolute_volume_management
Bug: 393657380

Change-Id: Idc2b217cbdc4e551312342e87a48a8e1346984b4