Merge "Load widget preview images before adding the rows to the adapter" into sc-dev am: dd19a24769 am: 50820e1fb5 am: db21421a2d

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/14965044

Change-Id: Iabaa18fba0093dc791db93f06862665f1ef4e71a