feat: Update the product options model and refactor the product module (#6685)

The changes in this PR are:
1. Change how product options are created and stored. The relationship changed from
`options --> option values <-- variants`
to
`options --> option values --> variant options <-- variants`

Now we can enforce non-duplicate option values, easier creation and updates of options, and more.

2. Refactors the product module. The product module did a lot of things in a non-ideal approach, and this is a step towards a more consistent usage of the base repository and methods exposed by a module. There is still work left to improve the module, but a large chunk of the changes are included in this PR


Things to do as a follow-up:
1. Remove many-to-many relationships  if an empty list is passed in the base repository.
2. Improve the typings of the module
3. Further cleanup and improvements (there are few questions that I need answered before I can improve the API)

integration-tests/modules/__tests__/price-lists/admin/price-lists.spec.ts

@@ -49,24 +49,23 @@ medusaIntegrationTestRunner({
           name: "VIP",
         })
         region = await regionModule.create({ name: "US", currency_code: "USD" })
-        ;[product] = await productModule.create([{ title: "test product" }])
+        ;[product] = await productModule.create([
+          {
+            title: "test product",
+            variants: [
+              {
+                title: "test product variant",
+              },
+            ],
+          },
+        ])
+
+        variant = product.variants[0]
 
         await pricingModule.createRuleTypes([
           { name: "Customer Group ID", rule_attribute: "customer_group_id" },
           { name: "Region ID", rule_attribute: "region_id" },
         ])
-
-        const [productOption] = await productModule.createOptions([
-          { title: "Test option 1", product_id: product.id },
-        ])
-
-        ;[variant] = await productModule.createVariants([
-          {
-            product_id: product.id,
-            title: "test product variant",
-            options: [{ value: "test", option_id: productOption.id }],
-          },
-        ])
       })
 
       describe("GET /admin/price-lists", () => {