Introduced `FileSystem.stat()` method, which returns the basic meta-data for a file used during snapshotting. This is used during snapshotting of input and output files, but not yet used during snapshotting of input and output directories. Added an implementation backed by native-platform that fetches this information using a single system call and that is much more efficient than using `File` or `Path` APIs. Added a fallback that is used when native-platform is not available. This fallback is currently also used for Windows due to some wiring issues in `FileSystemServices`.