Convert AudioFlinger create* arguments to AIDL

This is a first step in AIDLizing IAudioFlinger, where we are
converting the in/out arguments from create{Track,Record} to stable
AIDL and add their respective conversion functions.

Bug: 160253486
Test: atest CtsMediaTestCases:Audio*
      Manual verification of common playback and recording scenarios.
Change-Id: Iabb28472aedd90efbba673fb68574876528228df