Bug 24665: Add support for filtering by cash register

Bug 24665: Add support for filtering by cash register

This patch makes it possible to filter on cash register
on the cash register statistics page.

To test:
- Activate UseCashRegisters
- Create a cash register or more to use
- Create some manual fees and fines
- Pay some of them off
- Go to Tools > Cash register statistics
- Test if the new filter for cash registers works as it should

Signed-off-by: Kelly McElligott <kelly@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>