Bug 7896: Acq statistics wizard: add filters and cell values

Bug 7896: Acq statistics wizard: add filters and cell values

- Possibility to select for line and column: items.homebranch and
  items.ccode
- Possibility to filter on these fields
- Possibility to count unique biblios (count(distinct biblionumber)),
  ordered amount and spent amount (based on aqorders.datereceived)

Filtering on item homebranch and ccode works only on items that were
created at ordering or receiving (ie items are linked to an order)

Some refactoring is done, mainly replacing switch-like if statements by
given/when

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>