Bug 38390: Add subscriptions+count to vendors embed

This patch adds the subscriptions+count option to the embeddable enum
for the /vendors endpoint.

Test plan
1) Inspect the change to t/db_dependant/api/v1/acquisitions_vendors.t
   and confirm it's testing for the addition of subscriptions_count.
2) Run the above tests and confirm it passes

Note: For the above tests to pass, you will need to ensure your api
bundle is rebuilt after the patches are applied and restart plack.
`yarn build && restart_all` in ktd

Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
(cherry picked from commit ce5c7695e2)
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>

api/v1/swagger/definitions/vendor.yaml

@@ -119,6 +119,11 @@ properties:
     description: List of aliases
     items:
       $ref: "vendor_alias.yaml"
+  subscriptions_count:
+    type:
+      - integer
+      - "null"
+    description: Number of linked subscriptions
 additionalProperties: false
 required:
   - name

api/v1/swagger/paths/acquisitions_vendors.yaml

@@ -35,6 +35,7 @@
           type: string
           enum:
             - aliases
+            - subscriptions+count
         collectionFormat: csv
     responses:
       "200":

t/db_dependent/api/v1/acquisitions_vendors.t

@@ -36,7 +36,7 @@ my $t = Test::Mojo->new('Koha::REST::V1');
 
 subtest 'list() and delete() tests | authorized user' => sub {
 
-    plan tests => 40;
+    plan tests => 44;
 
     $schema->storage->txn_begin;
 
@@ -100,6 +100,13 @@ subtest 'list() and delete() tests | authorized user' => sub {
       ->json_is('/0/aliases/0/alias' => 'alias 1', 'alias 1 is embeded')
       ->json_is('/0/aliases/1/alias' => 'alias 2', 'alias 2 is embeded');
 
+    for ( 0 .. 1 ) {
+        $builder->build_object( { class => 'Koha::Subscriptions', value => { aqbooksellerid => $vendor->id } } );
+    }
+    $t->get_ok( "//$userid:$password@/api/v1/acquisitions/vendors" => { 'x-koha-embed' => 'subscriptions+count' } )
+        ->status_is(200)->json_has( '/0/subscriptions_count', 'subscriptions_count is embeded' )
+        ->json_is( '/0/subscriptions_count' => '2', 'subscription count is 2' );
+
     $t->delete_ok( "//$userid:$password@/api/v1/acquisitions/vendors/" . $vendor->id )
       ->status_is(204, 'SWAGGER3.2.4')
       ->content_is('', 'SWAGGER3.3.4');