Bug 30411: Put shelving location into its own column in holds queue

Bug 30411: Put shelving location into its own column in holds queue

To test:
1. Put some items on hold, make some bib level holds and some item
   level holds. Make sure that some of the holds have different shelving
   locations.
2. Build the holds queue. In KTD: perl
   /kohadevbox/koha/misc/cronjobs/holds/build_holds_queue.pl
3. Notice that the shelving location is in the same column as
   itemcallnumber
4. Apply patch and restart_all
5. Reload the holds queue and notice that shelving location now has it's
   own column.
6. Make sure you can sort by shelving location correctly.
7. Re-run the holds queue and apply the filter for shelving location.
   Make sure all your holds of that shelving location are shown.
8. While in the holds queue try usiong the 'Shelving location' filter on
   the left side of the page, make sure it works right.
9. Go to Admin > Table settings. Try hiding the shelving location column
   and reload the holds queue to make sure it is properly hidden.
10. Try hiding some other columns via Table settings to make sure all
    columns are still properly being hid.

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>