Add permission for dynamic AudioEffect attachment

Add signature or system permission
"android.permission.MODIFY_DEFAULT_AUDIO_EFFECTS" for AudioEffect APIs
allowing system services and applications to modify what effects get
automatically attached to streams/sources/devices of various types.

This permission is hidden for now, since this API is not yet approved
for mainline Android.

Bug: 67964202, 70300942
Test: None
Change-Id: I51b4e3a939e16221633448f646e5129e1a62dd23