Bug 29483: Further improve performance of script

Bug 29483: Further improve performance of script

This patch adds a few tests to cover more cases, and to highlight current functionality.

The script only allows renewal if all outstanding holds can be filled by available items.
This means we can return as soon as we have determined that not all holds can be filled.

I add FIXME and some explanatory comments - I will file a follow-up bug for those, but
I feel we can accept these improvements to the performance and deal with the issues
of how it 'should' work versus how it does work on another report.

To test:
1 - prove -v t/db_dependent/Circulation.t

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>