[webapi][XWALK-1330] Add 78 TCs for audiosystem

- Add 78 TCs for audiosystem
- Audiosystem is not supported in Tizen IVI now.

Impacted TCs (designed): New 78, Update 0, Delete 0
Unit test Platform: Tizen IVI
IVI test result summary: Pass 0, Fail 0, Blocked 0
Seems this file is to check the IDL attributes existence/type/readonly; not basic functionality checking.