Add the Subject subdivisions (MARC21 6XX $v $x $y $z)

[JoelleDosimont]

How it works

The subject subdivision (equivalent to the MARC21 fields 6XX $v $x $y $z) are not included in the JSON schema.

Improvement suggestion

1. Data model: add the Subject subdivisions (4 fields, optional and repeatable) as specified in the CONVERSION file.

- `genreForm_subdivision` = Form subdivision
    - description: Subject subdivision for a specific kind or genre of material (MARC 6XX$v)
    - placeholder: Example: Periodicals
- `topic_subdivision` = Concept subdivision
    - description:  Subject subdivision for a concept (MARC 6XX$x)
    - placeholder: Example: History
- `temporal_subdivision` = Time-span subdivision
    - description:  Subject subdivision for a period of time (MARC 6XX$y)
    - placeholder: Example: 500-1400
- `place_subdivision` = Place subdivision
    - description:  Subject subdivision for a place (MARC 6XX$z)
    - placeholder: Example: Mississippi

2. Display: those fields should be displayed, in order of appearance, in the pro and public interface, document detailed view, with - (space-hyphen-space) between the fields. Example:

3. Subject facet: all terms and subdivisions are distinct values within the facet.

* Example of one subject: Jérusalem (term) - Temple (topic subdivision) - Dans la Bible (topic subdivision)
* ...creates 3 values in the subject facet: Jérusalem / Temple / Dans la Bible

4. Index: those fields are indexed
* genreForm_subdivision as text with fr/de/it/en analyzer
* topic_subdivision as text with fr/de/it/en analyzer
* temporal_subdivision as text with fr/de/it/en analyzer
* place_subdivision as text