Add unit test for CellLayout making sure the reorder are valid and fix Multipage CellLyout

The new test generate hundreds of new boards using a fixed seed so the
test cases can be recreated if there is an error.

Some of the new clases where inside of CellLayoutBoard and moved
outside.

Flag: LEGACY FOLDABLE_SINGLE_PAGE DISABLED
Bug: 270395274
Test: ReorderAlgorithmUnitTest
Change-Id: I083fb6701b02b7c0b2cf24634ca71acb0c75902e