Respect original formatting/whitespace about json_repair

[mangiucugna]

This is an interesting issue because the library isn't stripping whitespaces if not trailing ones, the behavior is the one of json.dumps().
One could argue that I shouldn't "redump" a valid json but that would cause an issue when return_objects=True on a valid json. I could fix this by redumping only on return_objects=True but you see that it gets kinda complicated :)