lib : Add class name support

lib : Add class name support

- module kernel : Add output_class_name method to Object that display the object class name in console (debug only)
- module String : Add native_class_name method to Object (refinement) that return the class name in NativeString format
- module String : Add class_name method to Object (refinement) that return the class name in String format using native_class_name

Signed-off-by: Alexandre Terrasa <alexandre@moz-concept.com>