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

This reverts commit 5a1414c53f81118a35e8fb22231dcdd8ae335515.
Revert "[3/3] AudioFX: Add center frequency param to bassboost"

This reverts commit e6b968b3bdf549ac65d70c21e937104a052dd38f.