Merge "Add onSaveInstanceState support for GridPicker" into ub-launcher3-master am: e83b288c56 am: bbc373e6d8

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/ThemePicker/+/11659718

Change-Id: Ie88fadf628686acc22cf1419aa311a74dda913e7