Common: Rename the File namespace to FileUtil, to match the filename and prevent collisions.
Core: Add a new File class, obtainable from an Archive, and a stub implementation.
Core: Add a passthrough backend for the filesystem, exposed as SDMC.
Kernel: Add a File object and a getter for it from an Archive object.
Kernel: Add a File object and a getter for it from an Archive object.
Core: Add a method to obtain a Directory from an Archive.
Kernel: Add a Directory object and a getter for it from an Archive object.
FS: Implement OpenArchive, OpenDirectory, OpenFile and OpenFileDirectly calls.