Bug 24807: Add suppport for uncertain fields and ranges

Bug 24807: Add suppport for uncertain fields and ranges

To test:
1 - Have some records with uncertain dates in the 008
    19uu, 195u, etc.
2 - Index them in Elasticsearch
3 - Do a search that will return them
4 - Sort results by publication/copyright date
5 - Note odd results
6 - Apply patch
7 - Reindex
8 - Sorting should be improved

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>