Add test for updateRecord() with non-NULL move notifier.

The record need not be moved; however, if the DiskLoc returned in the
status is different than the old position of the record, then the
move notifier must have been called.
Start on tests for updateWithDamages().
Add updateWithDamages() tests for overlapping `DamageEvent`s.
Start on RecordIterator tests.
Add tests for RecordIterator that start at interior position.
Add tests for getIteratorForRepair().
Add tests for getManyIterators().
Add tests for truncate().
Add tests for truncate().