refactor: migrate pricing entities to DML models (#10335)

Fixes: FRMW-2810

## Breaking changes
There is only one breaking change

- The `min_quantity` and `max_quantity` properties are now consistently typed as numbers. Earlier, it was [typed as numbers](https://github.com/medusajs/medusa/blob/develop/integration-tests/http/__tests__/price-list/admin/price-list.spec.ts#L68-L69) in some API responses and as [string in others](https://github.com/medusajs/medusa/blob/develop/integration-tests/http/__tests__/price-list/admin/price-list.spec.ts#L186-L187). I did not go to the bottom of this inconsistency, but the tests reveals them.

Co-authored-by: Adrien de Peretti <25098370+adrien2p@users.noreply.github.com>

packages/modules/pricing/integration-tests/__fixtures__/price/index.ts

@@ -1,6 +1,7 @@
-import { SqlEntityManager } from "@mikro-orm/postgresql"
 import { Price } from "@models"
 import { defaultPricesData } from "./data"
+import { SqlEntityManager } from "@mikro-orm/postgresql"
+import { toMikroORMEntity } from "@medusajs/framework/utils"
 
 export * from "./data"
 
@@ -11,7 +12,7 @@ export async function createPrices(
   const prices: Price[] = []
 
   for (let data of pricesData) {
-    const price = manager.create(Price, data)
+    const price = manager.create(toMikroORMEntity(Price), data)
     prices.push(price)
   }