Bug 28826: Add FacetOrder system preference

Bug 28826: Add FacetOrder system preference

This bug adds a system preference to control ordering of facets and
adds the control to both Zebra and Elasticsearch

To test:
1 - Have a koha that can use both Zebra and ES
2 - Set 'displayFacetCount' to true
3 - Search in ES and Zebra
4 - Note facets in Zebra sorted alphabetically, ES by usage
5 - Apply patch, updatedatabase
6 - Search in ES and Zebra, facets are alphabetically sorted in both
7 - Find new syspref FacetOrder and set to 'by usage'
8 - Search in both engines, facets sorted by usage

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit ef40ba17aef792df332a11f7e0269c5684d913ac)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>