Merge "Revert "Revert "Extract assistant logic from NavigationBar to share with Taskbar""" into sc-v2-dev am: 1b79c1b5ce am: f9761acdf9

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/16337218

Change-Id: I2fe18744eb560b49d0c0e07881bbd4d2af156f25