code: Use std::span where appropriate (#6658)

* code: Use std::span when possible

* code: Prefix memcpy and memcmp with std::

src/common/file_util.h

@@ -191,7 +191,7 @@ void SetCurrentRomPath(const std::string& path);
 [[nodiscard]] const std::string& GetDefaultUserPath(UserPath path);
 
 // Update the Global Path with the new value
-const void UpdateUserPath(UserPath path, const std::string& filename);
+void UpdateUserPath(UserPath path, const std::string& filename);
 
 // Returns the path to where the sys file are
 [[nodiscard]] std::string GetSysDirectory();