file_util: Add a function to update the user path

Added a default value when sdmc and nand are empty

src/common/file_util.h

@@ -186,6 +186,9 @@ void SetCurrentRomPath(const std::string& path);
 // directory. To be used in "multi-user" mode (that is, installed).
 [[nodiscard]] const std::string& GetUserPath(UserPath path);
 
+// Update the Global Path with the new value
+const void UpdateUserPath(UserPath path, const std::string& filename);
+
 // Returns the path to where the sys file are
 [[nodiscard]] std::string GetSysDirectory();