oas: [15/n] improve oas schemas (#9216)

Improve OAS schemas [15/n]

Note: validation error will be fixed once #9218 is merged

www/utils/generated/oas-output/schemas/BaseCollection.ts

@@ -1,8 +1,52 @@
 /**
  * @schema BaseCollection
  * type: object
- * description: The product's collection.
+ * description: The collection's details.
  * x-schemaName: BaseCollection
+ * required:
+ *   - id
+ *   - title
+ *   - handle
+ *   - created_at
+ *   - updated_at
+ *   - deleted_at
+ *   - metadata
+ * properties:
+ *   id:
+ *     type: string
+ *     title: id
+ *     description: The collection's ID.
+ *   title:
+ *     type: string
+ *     title: title
+ *     description: The collection's title.
+ *   handle:
+ *     type: string
+ *     title: handle
+ *     description: The collection's handle.
+ *   created_at:
+ *     type: string
+ *     format: date-time
+ *     title: created_at
+ *     description: The date the collection is created.
+ *   updated_at:
+ *     type: string
+ *     format: date-time
+ *     title: updated_at
+ *     description: The date the collection is updated.
+ *   deleted_at:
+ *     type: string
+ *     format: date-time
+ *     title: deleted_at
+ *     description: The date the collection is deleted.
+ *   products:
+ *     type: array
+ *     description: The collection's products.
+ *     items:
+ *       $ref: "#/components/schemas/AdminProduct"
+ *   metadata:
+ *     type: object
+ *     description: The collection's metadata, can hold custom key-value pairs.
  * 
 */