AudioService: factor out sound effects handling

Move the code related to sound effects loading and playback
into a separate class SoundEffectsHelper.

Bug: 135763139
Test: make and run phone
Change-Id: I30a7d897d740b02943c68924074f14fae3c3eff8
Merged-In: I30a7d897d740b02943c68924074f14fae3c3eff8
2 files changed