Cleaning up some synchronous event registration in Views

> Removing broadcast receiver in ViewFlipper and AdapterViewFlipper
  as those are handled by windowvisibility
> Adding a delegate for event registration in TextClock and AnalogClock
  so that they can easily be overriden

Bug: 294352799
Test: Verified on device
Flag: N/A
Change-Id: Ib80f8c938019378fea3e243dc67ce6ff0765b256