audio: Provide code for parsing surround sound config from XML

The main change is to convert the result of parsing from XSDC
types to AIDL, and add a VTS test for IConfig.getSurroundSoundConfig.

Extra changes:
  - add 'Unchecked' suffix to conversion functions that do not
    wrap the result into ConversionResult;
  - enable more compile-time checks for the default AIDL service,
    fix issues found.

Bug: 205884982
Test: atest VtsHalAudioCoreTargetTest
Change-Id: Icf578b8d28647e6355ed5328599c77d2ca1234f9