Bug 14567: Add a browse interface to the OPAC

Bug 14567: Add a browse interface to the OPAC

This is an interface for quick and efficient browsing through records.

It presents a page at /cgi-bin/koha/opac-browse.pl that allows you to
enter the prefix of an author, title, or subject and it'll give you a
list of the options that match that. You can then scroll through these
and select the one you're after. Selecting it provides a list of records
that match that particular search.

To Test:
 1 - Apply patches
 2 - Update database (updatedatabase on kohadevbox)
 3 - Compile the CSS
   https://wiki.koha-community.org/wiki/Working_with_SCSS_in_the_OPAC_and_staff_client
   yarn build --view=opac on kohadevbox
 4 - Enable the new syspref OpacBrowseSearch
 5 - Have ES running and some records in it
     SearchEngine syspref set to Elasticsearch
 6 - Browse to opac home, click 'Browse search' link
for your site)
 7 - Test searching for author, title, and subject
 8 - Verify that results are returned in expected order
 9 - Experiment with fuzziness
     https://www.elastic.co/guide/en/elasticsearch/reference/5.6/common-options.html#fuzziness
     Options are: exact (0 edits), fuzzy (1 edit), very fuzzy (2 edits)
10 - Click any result and verify specific titles are correct
11 - Click through title to record and verify it is the correct record
12 - Test that disabling pref removes the link on the opac home

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>