The new grid migration algorithm

go/grid-migration-v2

When changing grid from option 1 to option 2, we calculate the diff and add the icons that are in option 1 but not option 2, to option 2's workspace, according to the reading order.

Test: manual and unit tests
Fixes: 144052802

Change-Id: Id01f69e90ce656a9b7c9051fed499807ee9ac0f7