Bug 22258: Elasticsearch: Add array as an alternative MARC format

Bug 22258: Elasticsearch: Add array as an alternative MARC format

Adds preference ElasticsearchMARCFormat that controls whether MARC records are stored as ISO2709/MARCXML or array. Array is searchable by field and also indexes all subfields in the _all field for searching.

Test plan:
1. Test that searching and indexing works with the patch without any changes.
2. Switch to array format and index some records.
3. Check e.g. the 008 field of a record and verify that the record can be found with the contents enclosed in quotes.
4. Check that it's possible to search for a specific field/subfield. Search query: marc_data_array.fields.655.subfields.a:Diaries
5. Check that tests still pass, especially t/Koha/SearchEngine/Elasticsearch.t

Signed-off-by: Michal Denar <black23@gmail.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>