Correct byte-key ordering so ascending comparisons place prefixes first and descending comparisons reverse that order. Rename the comparers to `ByteArrayLexicographicComparerAscending` and `ByteArrayLexicographicComparerDescending`, and update the default comparer.
This is a breaking change. Databases recording the old comparer names fail with `TreeComparerMismatchException` before loading segments. The error and documentation explain that affected databases must be exported with the previous version and rebuilt.