audio framework: manage stream volume per device

audio framework: manage stream volume per device

Improve volume management by keeping track of volume for each type
of device independently.
Volume for each stream (MUSIC, RINGTONE, VOICE_CALL...) is now maintained
per device.

The main changes are:
- AudioService now keeps tracks of stream volumes per device:
 volume indexes are kept in a HashMap < device , index>.
 active device is queried from policy manager when a volume change request
 is received
 initalization, mute and unmute happen on all device simultaneously
- Settings: suffixes is added to volume keys to store each device
volume independently.
- AudioSystem/AudioPolicyService/AudioPolicyInterface: added a device argument
to setStreamVolumeIndex() and getStreamVolumeIndex() to address each
device independently.
- AudioPolicyManagerBase: keep track of stream volumes for each device
and apply volume according to current device selection.

Change-Id: I61ef1c45caadca04d16363bca4140e0f81901b3f