Enable switch of getArg, getGet, getPost default value to be empty string instead of null

Why do we need this

Enable switch of getArg, getGet, getPost default value to be empty string instead of null

This allows direct passing from request input var to string validation functions. Previous to php 8.1 we could pass null to string processing and validation functions but this fails in php 8.1

Instead of switching default add gateway flag to override for now as we did with \sb\Gateway::$direct_view_render;

What to do

• update \sb\Request methods and http controller methods that use them