audioservice: add missing permission checks

AudioManager getAudioVolumeGroups() and getAudioProductStrategies()
Are @SystemApi and should be protected by MODIFY_AUDIO_ROUTING permission
but no check was done on server side.

Bug: 154934920
Test: atest AudioManagerTest
Change-Id: I8f48eb83d8c2f55248f90a47240fd1547a1c2297