Rename AssistUtilsBase -> AssistUtils am: b2ac210120 am: a8c9d7161f

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

Change-Id: I5d17902c7fe76dcdd07728fc4c7935e68aec82f4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>