Make AudioManager.getReportedSurroundFormats a TestApi

Access to the API needed from a tunnel mode CTS test.
TestAPIs dont work in CTS test if they intrenally call AudioSystem.
Changing getSurroundFormats and getReportedSurroundFormats to call
AudioService instead of AudioSystem.

Bug: 189823767
Test: atest android.media.cts.DecoderTest#testTunneledAudioPTSGapsAc3
Change-Id: If6287743f57b77d0eb2639e4a2e9409c7d778f06
Merged-In: If6287743f57b77d0eb2639e4a2e9409c7d778f06