Add MODIFY_DEFAULT_AUDIO_EFFECTS permission to shell

Add MODIFY_DEFAULT_AUDIO_EFFECTS permission to shell which
is needed to run GTS tests on @systemApis for
audio effects control.

Bug: 148703417
Test: run gts -m GtsAudioTestCases -t com.google.android.audio.gts.DeviceEffectTest#testCreateDeviceEffect
Change-Id: Iba579001aeffd85743850727135a6f536579ea17