add an explicit requireOrder argument to NamespaceDetailsTransient::getCursor()

The following assumption makes it difficult for NamespaceDetailsTransient::getCursor() to be used for index only projection by clients other than the query implementation.

        /** If no ParsedQuery was supplied, it's assumed no reordering will be applied. */

        bool requireOrder() const { return !_parsedQuery; }

It is straightforward to replace this with an additional argument to NamespaceDetailsTransient::getCursor().