chore(oas): [19/n] improve oas schemas (#9317)

- Improve OAS schemas [19/n]
- docs-generator: combine `Date | string` type to just `Date`.

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

@@ -1,8 +1,111 @@
 /**
  * @schema OrderItem
  * type: object
- * description: The item's detail.
+ * description: The order item's detail.
  * x-schemaName: OrderItem
+ * required:
+ *   - id
+ *   - item_id
+ *   - item
+ *   - quantity
+ *   - raw_quantity
+ *   - fulfilled_quantity
+ *   - raw_fulfilled_quantity
+ *   - delivered_quantity
+ *   - raw_delivered_quantity
+ *   - shipped_quantity
+ *   - raw_shipped_quantity
+ *   - return_requested_quantity
+ *   - raw_return_requested_quantity
+ *   - return_received_quantity
+ *   - raw_return_received_quantity
+ *   - return_dismissed_quantity
+ *   - raw_return_dismissed_quantity
+ *   - written_off_quantity
+ *   - raw_written_off_quantity
+ *   - metadata
+ *   - created_at
+ *   - updated_at
+ * properties:
+ *   id:
+ *     type: string
+ *     title: id
+ *     description: The item's ID.
+ *   item_id:
+ *     type: string
+ *     title: item_id
+ *     description: The ID of the associated line item.
+ *   item:
+ *     $ref: "#/components/schemas/OrderLineItem"
+ *   quantity:
+ *     type: number
+ *     title: quantity
+ *     description: The item's quantity.
+ *   raw_quantity:
+ *     type: object
+ *     description: The item's raw quantity.
+ *   fulfilled_quantity:
+ *     type: number
+ *     title: fulfilled_quantity
+ *     description: The item's fulfilled quantity.
+ *   raw_fulfilled_quantity:
+ *     type: object
+ *     description: The item's raw fulfilled quantity.
+ *   delivered_quantity:
+ *     type: number
+ *     title: delivered_quantity
+ *     description: The item's delivered quantity.
+ *   raw_delivered_quantity:
+ *     type: object
+ *     description: The item's raw delivered quantity.
+ *   shipped_quantity:
+ *     type: number
+ *     title: shipped_quantity
+ *     description: The item's shipped quantity.
+ *   raw_shipped_quantity:
+ *     type: object
+ *     description: The item's raw shipped quantity.
+ *   return_requested_quantity:
+ *     type: number
+ *     title: return_requested_quantity
+ *     description: The item's quantity that's requested to be returned.
+ *   raw_return_requested_quantity:
+ *     type: object
+ *     description: The item's raw return requested quantity.
+ *   return_received_quantity:
+ *     type: number
+ *     title: return_received_quantity
+ *     description: The item's quantity that's received through a return.
+ *   raw_return_received_quantity:
+ *     type: object
+ *     description: The item's raw return received quantity.
+ *   return_dismissed_quantity:
+ *     type: number
+ *     title: return_dismissed_quantity
+ *     description: The item's quantity that's returned but dismissed because it's damaged.
+ *   raw_return_dismissed_quantity:
+ *     type: object
+ *     description: The item's raw return dismissed quantity.
+ *   written_off_quantity:
+ *     type: number
+ *     title: written_off_quantity
+ *     description: The item's quantity that's removed due to an order change.
+ *   raw_written_off_quantity:
+ *     type: object
+ *     description: The item's raw written off quantity.
+ *   metadata:
+ *     type: object
+ *     description: The item's metadata, can hold custom key-value pairs.
+ *   created_at:
+ *     type: string
+ *     format: date-time
+ *     title: created_at
+ *     description: The date the item was created.
+ *   updated_at:
+ *     type: string
+ *     format: date-time
+ *     title: updated_at
+ *     description: The date the item was updated.
  * 
 */