Bug 15156: Add filter_by_amount_owed that's chainable

Bug 15156: Add filter_by_amount_owed that's chainable

This patch acts as an alternative here. We pull out the code from bug
11983 and extend it to support filtering of debts by branchcode and
debit_type.

The advantage of this approach is that we can add the filter into the
middle of a search chain to filter down an pre-existing search.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Emmi Takkinen <emmi.takkinen@koha-suomi.fi>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>