Merge "Move widget files into widget folder + add tests." into sc-dev am: a6554759aa

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/13661706

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Ic97ace8c1cb6e6f7ba3e9f926ff610ea2fb68828