Archives: Implemented ExtSaveData and SharedExtSaveData

They will be stored in /extsavedata/SDMC and /extsavedata/NAND respectively.
Also redirect some APT_A functions to their APT_U equivalents.
Implemented the gamecoin.dat file in SharedExtSaveData in the PTM module.
Implemented formatting the savegame.
Retake a previous savegame if it exists instead of reporting them as not formatted every time a game is loaded.

src/core/file_sys/archive_romfs.cpp

@@ -62,4 +62,9 @@ std::unique_ptr<DirectoryBackend> Archive_RomFS::OpenDirectory(const Path& path)
     return Common::make_unique<Directory_RomFS>();
 }
 
+ResultCode Archive_RomFS::Format(const Path& path) const {
+    LOG_WARNING(Service_FS, "Attempted to format ROMFS.");
+    return UnimplementedFunction(ErrorModule::FS);
+}
+
 } // namespace FileSys