Separates zone audio to different channels in car emulator

- rear seat buses (with "rear" in its address) uses right channel
- left channel otherwise

This behavior is enabled only if ro.aae.simulateMultiZoneAudio property
is turned on. To switch the behavior back and forth during runtime, one
has to restart the audioserver as well as car service after changing the
value via `adb shell setprop <key> <value>`. The most convenient way
would be to enable this flag at boot time as following

```
emulator -prop ro.aae.simulateMultiZoneAudio=true
```

Bug: 120299880
Test: manually on gcar_emu_x86-userdebug emulator
Change-Id: I61e542ca621f922dfafe7c5979bd4d13ab2fc57a