Fixing async inflation for nested RemoteViews

> Fixing isRootNamespace check
> Updating ViewTree when ViewStub is inflated
> Applying ViewGroupAction on previously found views instead of finding it again
  as the viewTree might have changed.

Test: am instrument -w -e class android.widget.RemoteViewsTest com.android.frameworks.coretests/android.support.test.runner.AndroidJUnitRunner
Bug: 32639592

Change-Id: I0815fb3a981efbc04fb0d080b81949985c2d9bc3