Bug 20600: Add filtering of ILL requests in list

Bug 20600: Add filtering of ILL requests in list

This patch adds the ability for the ILL request list in the staff
interface to be filtered by a number of criteria:

- Status
- Date placed
- Date modified
- Pickup branch
- Borrower card number

To test:
1) Apply patch
2) Ensure you have a reasonable range of ILL requests created
3) Navigate to the "View ILL requests" page
4) Choose one or more filtering criteria
5) Click "Search"
6) Observe the results are filtered to match the selected criteria
7) Click "Clear"
8) Observe your results are returned to their initial state
9) Repeat steps 4 -> 6 until you are happy.

Dates supplied by the /api/v1/illrequests API route were not conforming
to the preference specified by the dateformat syspref. This patch
addresses that.

It has been addressed as part of this bug since we are adding filtering
of requests by some date fields and, therefore, needed dates in a
predictable format.

To test:
1) Apply the patch
2) Ensure you have at least one ILL request created
3) Make a request to the /api/v1/illrequests endpoint
4) Observe that dates supplied for "placed_formatted" & "updated_formatted" conform to your
dateformat syspref.
5) Change your date format syspref, repeat steps 3 & 4

Signed-off-by: Magnus Enger <magnus@libriotech.no>
Works as advertised. Nice enh!

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>