Use UUID for Refering to Material Types

As decided in FOLIO-535, any kind of "controlled vocabulary" endpoint should follow a similar scheme.

CRUDing

GET|POST /cv-items/
GET|PUT|DELETE /cv-items/:uuid

Associations

In the "parent" record (like User or Item) we would include raw UUID/s directly in the associated record, using a scalar UUID field for many-to-one relations (e.g MT) or an array of UUIDs for the many-to-many relations (e.g PG):

{
  "username": "shale99",
  "patron_groups": ["123-456-789-123", "345-678-910-111"]
}

The PUT/POST on the record with proper UUID value should allow for updating associations. To get all users/items/etc with a given PG/MT/etc association we will use sarching/filtering.

Searching with CQL

Search/filter for items with a CV-item should be supported directly on the resource:

lastName="Doe" AND (patron_group == "123-456-789" OR patron_group == "112-113-114")

when constructing facet-like clickable filters on the left-hand side the UI will lookup all CV values (the assumption is that the list is short) and create name-to-uuid map for handling filtering.

The above sheme should be used for all newly constructed CV-like endpoints.