Bug 30280: Elasticsearch - Add 040f to Subject-heading-thesaurus-conventions (new...

Bug 30280: Elasticsearch - Add 040f to Subject-heading-thesaurus-conventions (new) authority mapping index field (MARC21)

This patch adds 040 $f to a new field Subject-heading-thesaurus-conventions authority index mapping.

To test:
1) Apply patch
2) Reindex using rebuild_elasticsearch.pl -r

If you don't have access to a terminal (in a sandbox for example)
2a) Go to Administration > Search engine configuration, click "Reset mappings" and confirm
2b) Then reindex

Sponsored-by: Lund University Library, Sweden
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>