[AudioManager] Add properties for the preferred device (#987)

[AudioManager] Add properties for the preferred device (#987)

* [AudioManager] Add properties for the preferred device to AudioStreamPolicy class

Signed-off-by: Sangchul Lee <sc11.lee@samsung.com>
* fixup! [AudioManager] Add properties for the preferred device to AudioStreamPolicy class

* fixup! [AudioManager] Add properties for the preferred device to AudioStreamPolicy class

* [AudioManager] Use null-conditional operator and ?? operator

Signed-off-by: Sangchul Lee <sc11.lee@samsung.com>
* [AudioManager] Remove codes checking device id of preferred device handle

Native API is now changed to return error if there's a difference of preferred
deivce id between server and stream info. handle.

Signed-off-by: Sangchul Lee <sc11.lee@samsung.com>
* fixup! [AudioManager] Remove codes checking device id of preferred device handle

Signed-off-by: Sangchul Lee <sc11.lee@samsung.com>