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)

packages/core-flows/src/handlers/product/update-product-variants.ts

@@ -1,5 +1,5 @@
 import { Modules, ModulesDefinition } from "@medusajs/modules-sdk"
-import { ProductTypes, UpdateProductVariantOnlyDTO } from "@medusajs/types"
+import { ProductTypes, UpdateProductVariantDTO } from "@medusajs/types"
 import { WorkflowArguments } from "@medusajs/workflows-sdk"
 
 type HandlerInput = {
@@ -14,18 +14,13 @@ export async function updateProductVariants({
 > {
   const { productVariantsMap } = data
   const productsVariants: ProductTypes.UpdateProductVariantDTO[] = []
-  const updateVariantsData: ProductTypes.UpdateProductVariantOnlyDTO[] = []
+  const updateVariantsData: ProductTypes.UpdateProductVariantDTO[] = []
   const productModuleService: ProductTypes.IProductModuleService =
     container.resolve(ModulesDefinition[Modules.PRODUCT].registrationName)
 
-  for (const [
-    product_id,
-    variantsUpdateData = [],
-  ] of productVariantsMap) {
+  for (const [product_id, variantsUpdateData = []] of productVariantsMap) {
     updateVariantsData.push(
-      ...(variantsUpdateData as unknown as UpdateProductVariantOnlyDTO[]).map(
-        (update) => ({ ...update, product_id })
-      )
+      ...variantsUpdateData.map((update) => ({ ...update, product_id }))
     )
 
     productsVariants.push(...variantsUpdateData)