Add haptic effect for the seekbar in Settings 2/n.

- for Audio balance, perform haptic feedback as the seekbar's progress value is the center/min/max value.
- screenshot, https://screenshot.googleplex.com/3xJUJkvJuXTUCqe

Bug: 174109628
Test: make -j42 RunSettingsRoboTests ROBOTEST_FILTER=BalanceSeekBarTest
Change-Id: I8b4ab37a2e635fb3b1ca2a9277a06b1e83f81bbb