Update existing Folder items' ranks to match their pre-permutation layouts.

With the new Folder permutation logic, we change the position of the items
when they are added to a Folder. This means that existing Folders will
now appear in a different order than the user arranged them in.

This change makes sure that when a user upgrades, their existing Folders
will appear untouched.

Note: We decided to priotize restoring the original layout of the Folder,
      as opposed to making sure the preview items remain the same. This
      is less destructive of users' data (we're changing the window into
      the Folder, but not the location of items when the Folder is open).

Bug: 63115141
Bug: 35064148

Change-Id: Ib0a28b4b50be089878ffc3e40bced89832e125bc