Bug 17018: Split AdvancedSearchTypes for staff and OPAC

Bug 17018: Split AdvancedSearchTypes for staff and OPAC

This patch adds a new system preference, OpacAdvancedSearchTypes, as an
OPAC-specific version of the AdvancedSearchTypes preference. Values from
AdvancedSearchTypes are copied to OpacAdvancedSearchTypes so that
behavior is consistent.

The patch also alters the output of the "Most popular" page so that:
1. The page heading is correct ("Most popular titles" instead of "Top
issues").
2. The table show both item type and collection whether or not the user
has submitted query with one of those fields as a filter.

To test, apply the patch and run the database update process.

- Go to Administration -> System preferences.
- Search for AdvancedSearchTypes. You should get two results, one for
  the OPAC preference and one for the staff interface.
- Check that the OpacAdvancedSearchTypes settings match the
  AdvancedSearchTypes settings.
- View the advanced search pages in the staff interface and OPAC to
  confirm that the tabs look correct.
- Change the OpacAdvancedSearchTypes and AdvancedSearchTypes settings to
  be different and confirm that each is applied separately to each
  interface.
- Enable the OpacTopissue system preference.
- View the "Most popular" page in the OPAC.
  - The page heading should be correct.
  - The OpacAdvancedSearchTypes settings should be reflected in the
    "Refine your search" sidebar: If "Collection" is checked, a filter
    for collection should appear. If "Item types" is checked, a filter
    for item types should appear.
  - The output of your search should include collection and item type
    regardless of what filters you've submitted.

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>