Add Container.Indexed.getItemIds(int, int) for a range of items (#8028)

Add Container.Indexed.getItemIds(int, int) for a range of items (#8028)

This permits optimization of data fetches from various containers
where getting single items by index in a loop might be costly.

Also add a helper method in ContainerHelpers to make it easier to
implement the new method where performance of fetching an id by index is
not an issue. SQLContainer still uses this helper instead of an
optimized implementation.