Revert "[3/3] AudioEffect: Add a stereo widener effect"

This reverts commit 933d363ecfd53a7ac8b86b446b21711d51f21c61.
Revert "[3/3] AudioFX: Add center frequency param to bassboost"

This reverts commit 8c6570eefeeeb404d208569a41218f7b85e538fa.