PRD-5313 - Crosstab UI and sorting fixes

Sorting was not applied on the second pass of a report run, breaking crossatab reports. Ensure that OK button is disabled for invalid crosstab configurations. This ensures that the create/edit crosstab dialog behaves correctly. Changed root-action for crosstab element from "Add Crosstab" to "Edit Crosstab" as this element should always have a crosstab group.