Bug 23204: Add script for exporting Elasticsearch mappings

Bug 23204: Add script for exporting Elasticsearch mappings

Test plan:

  - launch perl misc/search_tools/export_elasticsearch_mappings.pl >
    /path/to/my_mappings.yaml
  - set koha-conf.elasticsearch_index_mappings to
    /path/to/my_mappings.yaml,
  - go to admin -> Search engine configuration,
  - click on "Reset mappins",
  - check that your search fields and mappings are as expected

Signed-off-by: Bouzid Fergani <bouzid.fergani@inlibro.com>
Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>