feat: Add supported currencies to store model (#6562)

I ultimately went with having a flat list of settings for the store. It wouldn't be very difficult to change it if we wish to do so, but for now this keeps the codebase simpler

packages/store/src/models/store.ts

@@ -35,6 +35,9 @@ export default class Store {
   @Property({ columnType: "text", default: "Medusa Store" })
   name: string
 
+  @Property({ type: "array", default: "{}" })
+  supported_currency_codes: string[] = []
+
   @Property({ columnType: "text", nullable: true })
   default_sales_channel_id: string | null = null