Add support for custom script call from inherited Opauth controller

custom Controller_Opauth can return a result with an array to force a particular callback with a script (JS) echo.

e.g.
	class Controller_Opauth extends romaninsh\opauth\Controller_Opauth {

		.
		.
		
		function callback($data, $opauth) {
			.
			.
			$result = array(
	            'force_callback' => true,
	            'custom_script' => '<script>window.opener.$(".users").trigger("reload"); window.close();</script>'
	        );
	       
	        return $result;
	    }

	    .
	    .
	}