Fix minor b/c break in https://github.com/joomla/joomla-cms/pull/4292

This fixes a minor b/c break in https://github.com/joomla/joomla-cms/pull/4292 where in some cases you could get the InvalidArgumentException being thrown when you got a 303 message.

Cases involved passing in empty string or null as the message parameter meaning the check at https://github.com/joomla/joomla-cms/pull/4292/files#diff-11a160a70413114ea70faf547cd097ecR976 failed and these values became the moved parameter (and weren't booleans or integers).

This adds a unit test for that scenario and fixes it. Of course all of this relates to the old redirect method and so of course is deprecated.