Add default list setting (#875)

Co-authored-by: Sytone <github@sytone.com>
Reviewed-on: https://kolaente.dev/vikunja/api/pulls/875
Reviewed-by: konrad <konrad@kola-entertainments.de>
Co-authored-by: sytone <kolaente@sytone.com>
Co-committed-by: sytone <kolaente@sytone.com>

pkg/swagger/swagger.yaml

@@ -1178,6 +1178,11 @@ definitions:
     type: object
   v1.UserSettings:
     properties:
+      default_list_id:
+        description: |-
+          If a task is created without a specified list this value should be used. Applies
+          to tasks made directly in API and from clients.
+        type: integer
       discoverable_by_email:
         description: If true, the user can be found when searching for their exact
           email.