Testing uses cas compare function, make this order independent

Some tests compare two CASes for (approximate) equality, but the compare requires the items in the CASes be in the same "order". Newer iterator implementations of bag and sets no longer necessarily preserve ordering, so the compare may fail even though the CASes contain the same FeatureStructures. Improve the CAS compare test to permit comparing equal without needing the same ordering.

Remove extra test class CasComparerViewChange, have its 2 users directly call the compare function.