Rename AssistUtilsBase -> AssistUtils am: b2ac210120

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/24555400

Change-Id: Idde965260aef41cd3fe662557051ccc92418e8c0
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>