Bug 39830: Add order claim object definition

This patch adds the required mapping in
`Koha::Acquisition::Order::Claim` and adds it's definition to the API
spec.

To test:
1. Apply the patches
2. Verify the mapping makes sense and conforms to the current style and
   API coding guidelines.
3. Run:
   $ ktd --shell
  k$ prove xt/api.t
=> SUCCESS: Tests pass
4. Sign off :-D

Signed-off-by: Emmi Takkinen <emmi.takkinen@koha-suomi.fi>
Signed-off-by: Martin Renvoize <martin.renvoize@openfifth.co.uk>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>

Koha/Acquisition/Order/Claim.pm

@@ -29,8 +29,22 @@ Koha::Acquisition::Order::Claim - Koha Claim Object class
 
 =head2 Class methods
 
+
+=head3 to_api_mapping
+
+This method returns the mapping for representing a Koha::Patron object
+on the API.
+
 =cut
 
+sub to_api_mapping {
+    return {
+        id          => 'order_claim_id',
+        ordernumber => 'order_id',
+        claimed_on  => 'date_claimed',
+    };
+}
+
 =head2 Internal methods
 
 =head3 _type

api/v1/swagger/definitions/order_claim.yaml

@@ -0,0 +1,14 @@
+---
+type: object
+properties:
+  order_claim_id:
+    type: integer
+    description: Internally assigned order claim identifier
+  order_id:
+    type: integer
+    description: Internally assigned order identifier
+  date_claimed:
+    type: string
+    format: date
+    description: Date the claim was recorded
+additionalProperties: false

api/v1/swagger/swagger.yaml

@@ -142,6 +142,8 @@ definitions:
     $ref: ./definitions/merge_biblios.yaml
   order:
     $ref: ./definitions/order.yaml
+  order_claim:
+    $ref: ./definitions/order_claim.yaml
   patron:
     $ref: ./definitions/patron.yaml
   patron_account_credit: