Configures this instance to sort its results by some property and order.
This method will have the database perform a sort by some property identified by
propertyIdentifier must return a scalar property of
InstanceType that can be compared. The
indicates the order the returned rows will be in. Multiple sortBys may be invoked on an instance;
the order in which they are added indicates sort precedence. Example:
var query = Query<Employee>() ..sortBy((e) => e.name, QuerySortOrder.ascending);
void sortBy<T>(T propertyIdentifier(InstanceType x), QuerySortOrder order);