GPII-434: Refactoring following removal of Acceptance test definitions up into universal. These tests are run from here as acceptance tests using the universal definitions. Work on registry settings handler to implement the new "undefined value is deletion" semantic. Test cases using new Windows API call RegDeleteValueEx. New driver structure to mirror that in universal. Test cases are still not passing reliably - it appears there is an asynchronous interaction between desktop theme settings and cursor settings - even more power is required in the main lifecycle to repeatedly retry setting settings.