Merge "Implement the custom style flow part 1" into ub-launcher3-master am: 42a7a348fb am: 851643a073

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/ThemePicker/+/11650326

Change-Id: Ib73f59e7566235e63caba3d6400195f53a14359d