Bug 33174: Add warning about how many holds are being cancelled

Bug 33174: Add warning about how many holds are being cancelled

To test:
1. Apply patch
2. Find or make a record with many holds on it.
3. Go to the Holds tab ( request.pl ).
4. Select some hodls to cancel and press "Cancel selected"
5. A modal popup will appear. Notice the warning telling you exactly how many holds you are about to cancel. Confirm the count is accurate.
6. Try using the select all button and make sure the warning is accurate.
7. Make sure you can cancel the holds.

Signed-off-by: Sally <sally.healey@cheshiresharedservices.gov.uk>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>