Enable Multi stores

**First open multiple stores ** Path: [Settings] - [System Settings] - [Basic Settings] - check [Enable Multi Stores]

Function Description：

1. Separate management can be realized between the store and the warehouse inventory after the checking.
2. Multi-store setting can not be closed if there are already multiple stores.

Add Stores  ————————————————————

Path: [Settings] - [Merchant Management] - [Store Management] - [Add Stores]