Key changes:
- Add `MacOSSnapshot` class implementing `SnapshotBase`
- Add helper scripts for creating, finding, and removing APFS snapshots
- Update `SnapshotUtility` to initialize macOS snapshots
- Enable `snapshot-policy` option for macOS in `Options.cs`
- Update build configuration to include APFS scripts
- Update snapshot test utility with macOS support
This fixes#6409