Merge "Have an interface for WidgetsSearchBar so Nexus Launcher can override the search bar." into sc-dev am: f8cf4c59b7

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/13827977

Change-Id: Ib9404e4cbb6a3b39b2945d2d43a3cce2bc07ff90