Chore/rm main entity concept (#7709)

**What**
Update the `MedusaService` class, factory and types to remove the concept of main modules. The idea being that all method will be explicitly named and suffixes to represent the object you are trying to manipulate.
This pr also includes various fixes in different modules

Co-authored-by: Stevche Radevski <4820812+sradevski@users.noreply.github.com>
Co-authored-by: Oli Juhl <59018053+olivermrbl@users.noreply.github.com>

integration-tests/modules/__tests__/store/admin/store.spec.ts

@@ -27,7 +27,7 @@ medusaIntegrationTestRunner({
       })
 
       it("should correctly implement the entire lifecycle of a store", async () => {
-        const createdStore = await service.create({
+        const createdStore = await service.createStores({
           name: "Test store",
           supported_currency_codes: ["usd"],
         })
@@ -56,8 +56,11 @@ medusaIntegrationTestRunner({
           })
         )
 
-        await service.delete(createdStore.id)
-        const listedStores = await api.get(`/admin/stores?id=${createdStore.id}`, adminHeaders)
+        await service.deleteStores(createdStore.id)
+        const listedStores = await api.get(
+          `/admin/stores?id=${createdStore.id}`,
+          adminHeaders
+        )
         expect(listedStores.data.stores).toHaveLength(0)
       })
     })